Analysis of power lithium battery 18650 recycling technology

　　1 Overview of technical route

　　For retired power batteries, there are currently two feasible methods of disposal: one is cascade utilization, in which the retired power lithium batteries are used in fields such as energy storage as carriers of electrical energy, thereby fully utilizing the remaining value; the other is dismantling Decomposition recycling involves discharging and dismantling retired batteries to extract raw materials for recycling. At present, only lithium iron phosphate batteries can exert their residual value through cascade utilization, and batteries made of ternary materials are still mainly dismantled and recycled.

　　Recycling process of used lithium batteries

　　1.1 Research progress of physical separation methods

　　Jin Yongxun and others used vertical shears, graded wind shakers and vibrating screens to classify, crush and sort waste lithium-ion batteries, and finally obtained light olefin products, metal products and electrode materials with high added value. The mixed powder of cathode material is treated at high temperature in a muffle furnace and then separated by flotation. The main advantages of the flotation method are that it does not add new pollution, consumes less energy, and the outer casing can be recycled. However, there are also some disadvantages, such as the significantly reduced charge and discharge performance of new synthetic batteries.

　　Daniel proposed a spouted bed elutriation technology based on physical sorting. The process is mainly divided into two steps: first, classify waste lithium-ion batteries according to the quality of each metal and its chemical composition; second, use mechanical Methods (grinding, sieving, and elutriation) are used to separate different metal substances. The metal recovery rate can reach 80%. There is also metal mixing in recovery, that is, the resolution of different metals by this method is slightly poor. Currently, spouted bed elutriation technology is a relatively simple and low-cost option for recycling and separating different metal substances from used lithium-ion batteries.

　　1.2 Research progress of pyrometallurgy

　　Ou Xiuqin and others used pyrometallurgy to recover valuable metals in used lithium-ion batteries. The specific process is as follows: peeling off the shell of used lithium-ion batteries, recovering the valuable metals in the shell material, and mixing the battery core with coke and limestone. , after reduction and roasting, the metal copper, cobalt, nickel, etc. are combined to form a carbon-containing alloy, and then continue to undergo deep processing. The entire process is completed at high temperature.

　　Sony/Sumitomo of Japan conducted a systematic study on the pyrometallurgical treatment of used lithium-ion batteries. The results showed that the batteries can self-decompose if unprocessed and undisassembled used lithium batteries are directly incinerated at temperatures below 1000°C. Separation, the residue after incineration contains metals such as iron, copper, aluminum, etc., and then through screening, magnetic separation and other methods to separate valuable metals for recycling and reuse. The recovery rate of metal elements is high, but the recovery rate of metal elements is high. Room for improvement.

　　Based on the research of Japan's Sony/Sumitomo Corporation, the French SNAM Company further studied the thermal decomposition of waste lithium-ion batteries and developed pyrolysis and magnetic separation technology. Its pyrolysis temperature is 100~200°C lower than that of Japan. The recovery rate of valuable metal elements is also higher than that in Japan.

　　1.3 Research progress of hydrometallurgy

　　Nam Junmin et al. broke through the limitations of a single method and combined the solvent extraction method with the precipitation method. They first leached the battery shell with an alkali solution, dissolved the positive and negative electrode materials of the battery with a solution of hydrogen peroxide and sulfuric acid mixed in proportion, and then Different extraction agents are used to selectively extract copper, manganese, cobalt and other metal elements. The recovery rate of various metals reaches more than 96%. Then sodium carbonate is used to separate the metallic lithium in the form of precipitation (such as lithium carbonate).

　　Tang Xincun and others improved the traditional precipitation treatment method to avoid problems such as strong acid corrosion and tail liquid pollution. They used ammonium bicarbonate to remove aluminum, yellow sodium ferrosite to remove iron, sodium carbonate to remove copper, and then used oxidation precipitation to remove manganese. After this series of impurity removal processes, a pure cobalt-containing solution is finally obtained, and the cobalt recovery rate is greatly improved, exceeding 98%.

　　Jinsik et al. proposed a new method for recovering cobalt oxide from lithium cobalt oxide batteries. The specific process flow is: slowly heat nitric acid, add used lithium-ion batteries to the hot nitric acid, and after the lithium carbonate is dissolved, metal cobalt is recovered through electrodeposition. The total recovery rate of cobalt element can reach more than 80%, and metal lithium element The recovery rate is also relatively high. The pH value of the solution is controlled at 2.4~2.7, and the electrode pads are made of titanium metal.

　　Zhou Chunshan et al. used anion exchange resin to study the anion exchange separation of metal ions. After comparing the exchange effects of several anion exchange resins, it was found that the 201-7 anion exchange resin has the best effect. The specific experimental method is: add ammonium chloride solution to the positive and negative electrode materials of the lithium ion battery, adjust the pH value to about 4.0, separate the cobalt ions, and then elute the metal ions from the 201-7 anion exchange resin. This method has the advantages of high cobalt recovery rate, good separation effect, and simple operation.

　　Wang Xiaofeng et al. integrated the advantages of ion exchange method and complex method, and based on the principle of ion exchange method, used mixing method to effectively exchange copper ions in the solution with suitable self-made ion exchange resin. This method achieves the separation and recovery of multiple metal elements in used lithium-ion batteries under normal temperature and pressure, with the recovery rates of cobalt and nickel reaching 89.9% and 84.1% respectively.

　　1.4 Research progress of bioleaching method

　　Mishra et al. used Ferrobacter acidophilus to recover cobalt and lithium from used lithium-ion batteries, and studied the effects of leaching time, temperature, stirring speed and other factors on the leaching effect of metallic cobalt from used lithium-ion batteries. The results show that although this method provides a new method for cobalt recovery, the leaching rate of lithium cobalt oxide by Ferrobacter acidophilus is very low, and strains with higher leaching rates need to be cultivated in the future.

　　2 Cascade utilization technology of decommissioned power lithium batteries

　　The cascade utilization of power lithium batteries is an intermediate link between new energy vehicles and power lithium battery 18650 resource utilization. Its significance lies in the entire battery life from battery raw materials - batteries - battery systems - automotive applications - secondary use - resource recycling - battery raw materials. Considering the periodic use, battery costs can be reduced and environmental pollution avoided. The recycling process of power lithium batteries is as shown [18].

　　The whole life cycle of power battery recycling in my country

　　Generally speaking, when the performance of a power battery drops to 80% of its original performance, it will not meet the standards for use in electric vehicles, but it still has the ability to continue to be used in energy storage systems, especially small-scale decentralized energy storage systems, such as Smooth and stabilize the output power of intermittent renewable energy generation such as wind energy and solar energy, implement peak shaving and valley filling, reduce the contradiction between supply and demand of electricity load, and meet the requirements of two-way interaction of smart grid energy. In addition, retired power lithium batteries can also be used in low-speed electric vehicles, such as electric bicycles and electric motorcycles.

　　2.1 Combined solar power generation system

　　It is an independently operating photovoltaic power generation system. The system structure includes major components such as solar cell arrays, energy storage battery packs, and inverters.

　　Photovoltaic power generation system

　　Usually, due to the change in solar radiation intensity, the output energy and power of the photovoltaic power generation system will always fluctuate, causing the user load to be unable to obtain a sustained and stable electric energy response. By assembling energy storage batteries in a photovoltaic power generation system, the storage and stabilization of electrical energy by the energy storage battery pack can greatly enhance the power supply performance of the system.

　　2.2 Combined wind power generation system

　　It is an independently operating wind power generation system, which usually consists of wind turbines, energy-consuming loads, energy storage battery systems, controllers, inverters, AC loads and other parts.

　　wind power system

　　Wind power generation devices are mainly divided into two operating modes, grid-connected operation and independent operation. In the process of independent operation, since wind energy cannot provide very stable energy, without the cooperation of energy storage systems or other power generation systems, it will be difficult for wind power generation equipment to ensure the reliability and stability of power supply. The introduction of energy storage systems into wind power generation technology can effectively suppress wind power power fluctuations, smooth output voltage, and improve power quality.

　　2.3 Combined power grid peak regulation

　　It is a battery grid peak shaving system. The system usually consists of a monitoring and protection system, a battery module composed of single secondary batteries, a battery management system (BMS), and a bidirectional energy storage converter.

　　Battery grid peak shaving system

　　By charging the electricity from the power grid at low load times through the power grid lines into different battery energy systems through special chargers, it can meet the power needs of urban electric buses, taxis and social vehicles. In addition, urban households and communities are equipped with a battery energy storage box, which can be charged at night when the power grid is under low load, and the reserve power supply is used to provide electrical energy during the day, which can also achieve the effect of peak shaving and valley filling.

　　2.4 Joint mobile base station

　　It is a lithium iron phosphate battery system, which usually consists of a battery management system, a battery pack, and a detection circuit module.

　　Schematic diagram of lithium iron acid battery system

　　The backup power supply of the mobile base station continues to work under float charge condition, and the battery voltage value continues to be 3.65V. At this voltage, both the battery plates and the electrolyte are in a stable state. Therefore, it can be seen from the characteristics of recycled batteries that recycled power lithium batteries can also be used in mobile base stations.

　　3 Dismantling and recycling technology of scrapped power lithium batteries

　　The recycling process of power batteries is generally divided into pre-processing processes such as discharge, dismantling, crushing, and sorting. Then the metal casing, electrode materials, etc. in the battery are separated, and then the electrode materials are processed through a specific recycling process, and finally screened to obtain useful materials. value of metal material. The recycling process of electrode materials generally includes three categories: chemical recycling, physical recycling and biological recycling. According to different processing methods, the chemical recycling process is divided into wet recycling technology and fire recycling technology, because biological recycling technology needs to be processed in a specific environment. can be realized, it is still in the laboratory research stage [19].

　　3.1 Physical recycling process

　　(1) Physical recycling process

　　Physical method recycling technology refers to the internal components of used power batteries, such as electrode active materials, current collectors and battery shells, through a series of means such as crushing, screening, magnetic separation, fine crushing and classification to obtain valuable products. Then proceed to the next step of the recycling process. Although the processing efficiency of physical dismantling and recycling is lower, the process is very environmentally friendly because no additional chemicals are consumed. Physical recycling process, as shown:

　　Physical method recycling process

　　Generally speaking, low temperature can greatly reduce the chemical reactivity of lithium compounds. The low-temperature ball milling method has the advantages of simple process, environmental friendliness, and low cost. The American company Toxco crushes the battery at -198°C and adds solid NaOH [20] to convert the lithium in the electrode material into LiOH, and adds additives to generate Li2CO3, which is separated from the plastic after ball milling. There are research reports [21] that LiFePO4 electrode material has a larger capacity (close to the theoretical value of 170mAh/g) after low-temperature treatment and simple recycling. Mitsubishi uses liquid nitrogen to freeze used batteries and then disassembles them [21]. The plastics are sorted, crushed, magnetically separated, and washed to obtain steel. They are vibrated and separated. After washing with a sorting sieve, copper foil is obtained. The remaining particles are burned to obtain LiCoO2. , the exhausted gas is absorbed by Ca(OH)2 to obtain CaF2 and Ca3(PO4)2.

　　(2) Economic analysis of physical recycling process

　　Through a survey of a domestic power battery physical recycling company, it was found that in the power battery recycling process, the costs are mainly concentrated in the stages of raw material recycling, battery disassembly pre-treatment, wastewater treatment, labor costs, etc. Table 3-1 shows the waste per ton Where the main costs go during battery disposal. Among them, the average recycling cost of used ternary batteries is 8,900 yuan/t, and the average recycling cost of lithium iron phosphate batteries with poor quality after cascade utilization is 4,000 yuan/t[19].

　　Table 1 Recycling and processing cost of used batteries per ton (yuan)

　　Through survey data, it can be seen that the average cost of recycling and dismantling ternary batteries per ton is 13,264 yuan, and the average cost of recycling and dismantling lithium iron phosphate batteries per ton is 8,364 yuan.

　　The large amount of valuable metals contained in power batteries is the main source of revenue for battery recycling. In particular, the rise in prices of nickel, cobalt, manganese, lithium and other metal materials in recent years has played a huge role in promoting the field of power battery disassembly and recycling. Table 2 shows the recycling efficiency of physical disassembly of used power batteries per ton of ternary materials and the main benefits of each material.

　　Table 2 Disassembly and recycling efficiency and revenue of ternary material batteries

　　Therefore, the average revenue from dismantling and recycling valuable metals and materials per ton of ternary material batteries is 16,728 yuan. In addition, after investigation, the income from dismantling of lithium iron phosphate batteries was also analyzed. The efficiency and income of dismantling and recycling materials of used lithium iron phosphate batteries are shown in Table 3-3. Therefore, the income from dismantling each ton of lithium iron phosphate batteries to recover valuable metals and materials is approximately 7,703 yuan.

　　Table 3 Lithium iron phosphate battery disassembly recycling efficiency and revenue

　　From the previous analysis of data, it can be seen that the dismantling cost of recycling a ton of ternary material batteries using physical methods is 13,264 yuan, and the income gained from selling the valuable materials obtained after disassembly is 16,728 yuan. Therefore, the dismantling and recycling of ternary material batteries per ton Yuan battery can make a profit of 3,464 yuan; while the dismantling cost of lithium iron phosphate battery per ton is 8,364 yuan, and the income is 7,703 yuan, so the disassembly and recycling of lithium iron phosphate battery will lose 661 yuan per ton.

　　3.2 Wet recycling process

　　1) Wet recycling process

　　The dismantling and recycling technology used by most enterprises in our country is wet recycling technology. Using this technology requires disassembling and pre-processing used batteries and dissolving them in acid and alkali solutions to extract some valuable metal elements, and then undergo ion exchange and Electrodeposition and other methods are used to extract the remaining valuable metals. In order to improve the extraction efficiency of metals, this process requires scrapped lithium batteries to be carefully classified according to the chemical composition of the battery materials before crushing, so as to use leach solutions of different properties. This process can be used alone or in combination with high-temperature metallurgy to further recover Fe, Al and rare earth metals from the fine powder containing metals and metal oxides produced by screening the solid residue obtained after incineration. The wet recycling process flow chart is given, and the details are as follows:

　　(1) Leaching process

　　1 Acid leaching

　　Acid leaching is based on the principle that the metal oxide of the battery cathode material is dissolved in acid. According to different pretreatment methods, the leaching process is divided into two types: direct leaching and indirect leaching. Direct leaching involves simply disassembling the battery and leaching it together with the current collector. Indirect leaching is to first separate and recover the current collector aluminum foil, copper foil and active materials before leaching. Generally, acid and alkali are used to dissolve the electrode materials. The result of acid leaching is that metal ions are present in the leaching solution, and then the target metal elements are separated and extracted. Alkali leaching is to first dissolve the current collector aluminum foil in strong alkali. After filtration and separation, the valuable metals are present in the filter residue, and the filter residue is further acid leached. There are many types of acids, detailed analysis is as follows.

　　A Inorganic acid leaching. Commonly used acids in acid leaching include hydrochloric acid, nitric acid, sulfuric acid and other inorganic acids. Among them, hydrochloric acid has the best leaching effect. Mix lithium cobalt oxide with 4 mol of hydrochloric acid and keep the temperature at 80°C. The cobalt leaching rate can reach 99% after 1 hour. However, hydrochloric acid is highly volatile and will produce toxic gas chlorine during the reaction. Nitric acid is also volatile.It is volatile and will generate toxic gases of nitrogen oxides and is expensive. Therefore, in actual production, sulfuric acid, which is cheaper and has a higher boiling point, is often used for acid leaching. In order to improve the leaching rate of sulfuric acid, a reducing agent can be added to the sulfuric acid. It is found that the leaching speed is increased and the leaching time is greatly shortened. Yang et al. used a HCl+H2O2 system to jointly leach waste lithium-ion battery materials to recover metal Li, with a recovery rate as high as 99.4%. Phosphoric acid is weakly acidic, but has a dual role. It can be used as an acid leaching electrode material and as a precipitant for cobalt ions to generate Co3 (PO4) 2. It is also often used in lithium battery 18650 recycling.

　　B Organic acid leaching. Most of the inorganic acids selected are strong acids, which will corrode equipment, and produce toxic gases during the production process, posing a threat to the health of workers. Therefore, people have tried to use environmentally friendly organic acids to replace inorganic acids for acid leaching, such as oxalic acid, citric acid, malic acid, ascorbic acid, etc., and have achieved certain results. Nayaka et al. used two organic acids, maleic acid and iminodiacetic acid, to leach the metal elements cobalt and lithium in used lithium-ion batteries, and the leaching effect was good. The use of organic acids in the acid leaching process avoids secondary environmental pollution caused by inorganic acids. However, organic acids are more expensive and the leached metal ions are not easy to separate, so they are rarely used in the acid leaching process.

　　C Reducing acid leaching. Since H2O2 is easy to decompose when heated, some researchers have considered directly using reducing acid to leach valuable metals based on the excellent leaching effect of acid plus reducing agent. Experimental studies have shown that it is feasible. Jun Lu et al. used the organic weak acid L-ascorbic acid vitamin for acid leaching treatment. L-ascorbic acid has strong reducing properties and can replace H2O2 as a reducing agent. After optimizing the test conditions, the final recovery rates of Co and Li can reach 94.8 respectively. % and 98.5%. Moreover, L-ascorbic acid is a weak acid, which avoids secondary pollution to the environment caused by the use of strong acids.

　　2 Bioleaching

　　Bioleaching of valuable metals is also a type of hydrosmelting of lithium battery 18650 materials. In recent years, this technology has attracted widespread attention from scientific researchers. Use microbial metabolism to generate a variety of organic acids, adjust the solution environment, and dissolve metal ions. Studies have found that when Aspergillus niger uses sucrose as an energy source, it can metabolize to produce a variety of organic acids, such as gluconic acid, citric acid, malic acid, oxalic acid, etc., which have a good leaching effect on metals in used batteries. However, due to the high requirements for microbial fungus culture conditions and low leaching rate compared with acid, biological hydrometallurgy only remains in the laboratory research stage and has not been applied on a large scale.

　　(2) Metal ion separation and extraction process

　　In hydrosmelting, after waste lithium-ion battery materials are leached, usually valuable metal elements such as nickel, cobalt, manganese, lithium, and aluminum exist in the leachate in an ionic state, and need to be selectively and gradually separated, extracted, and recycled. At present, the main separation and extraction methods include chemical precipitation separation, organic solvent extraction, electrodeposition, etc.

　　1 Chemical precipitation method

　　The chemical precipitation method refers to a method that uses a precipitant to selectively react with metal ions to form a refractory precipitate, which is then separated and extracted through filtration. The selection of precipitating agent is mainly based on the ionic characteristics of the leachate. During this process, attention needs to be paid to the control of the pH value and the amount of precipitant added to avoid the formation of a sol that is difficult to filter and separate. Commonly used precipitants include alkaline sodium salts such as sodium hydroxide, sodium carbonate, and sodium phosphate, ammonium salts such as ammonium chloride, ammonium oxalate, and ammonium bicarbonate, as well as oxalic acid, phosphoric acid, and potassium permanganate. The chemical precipitation method is simple to operate and has a high recovery rate, so it is suitable for current battery recycling production. However, co-precipitation often occurs in chemical precipitation methods, resulting in difficulty in separation of target metals and metal loss. Therefore, the precipitant should be carefully selected during specific operations.

　　2 Extraction method

　　The extraction method refers to the use of organic reagents to extract and recover valuable metal elements in used lithium batteries. It has the advantages of low energy consumption, good separation effect, high purity of metal separation, and mild operating conditions. Commonly used extraction agents include 2-hydroxyl -5-Nonylbenzaldehyde oxime (N902, Acorga M5640), bis(2,4,4-trimethylpentyl)phosphinate (Cyanex272), 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507, PC-88A), di(2-ethylhexyl) phosphate (P204, D2EHPA) and trioctylamine (TOA), etc. During the test process, according to different separation target metal ions, people should choose the appropriate Extractant and extraction conditions. The study found that the mixed extraction agent has a good synergistic effect, and the extraction effect is significantly better than that of a single extraction agent. However, the extraction and separation method uses a large number of chemical reagents, causing certain pollution to the environment, and the price of the extraction agent is relatively high, so it has certain limitations in metal recovery applications.

　　3 Electrodeposition method

　　The electrodeposition method refers to a method in which metal ions in the leach solution undergo an electrochemical reduction reaction at the cathode under the action of an external electric field to obtain the target metal. By analyzing the electrodeposition mechanism, FREITAS et al. investigated the effects of different pH values on metal nucleation and growth mechanisms, and explored a method of recycling cobalt, copper and other metals in lithium-ion batteries by constant-potential electrodeposition, with good recovery results. The electrodeposition method has the advantages of simple operation, relatively high product purity and recovery rate. The technology is very mature and has been widely used in industrial production. However, this method consumes a lot of electrical energy, and the active material needs to be purified before electrodeposition to avoid metal ion co-deposition.

　　Wet recycling process

　　2) Economic analysis of wet recovery process

　　Through investigation, it was found that the cost of the wet recycling process mainly comes from the cost of raw material recycling, wastewater and waste treatment, etc. Table 4 shows the main cost direction per ton of used battery processing.

　　Table 4 Cost of wet recycling process per ton of used batteries

　　Therefore, the average cost of processing 1 ton of ternary batteries in the wet recycling process is 14,815 yuan, and the average cost of processing 1 ton of lithium iron phosphate batteries is 9,915 yuan.

　　In addition, the wet recycling process is more efficient in recycling valuable battery materials, so the benefits are more obvious. Tables 5 and 6 show the main benefits of each material obtained by processing 1 ton of ternary batteries and lithium iron phosphate batteries using the wet recycling process.

　　Table 5 Recycling efficiency and revenue of ternary material battery wet recycling process

　　Table 6 Recycling efficiency and revenue of lithium iron phosphate battery wet recycling process

　　From the above data, it can be concluded that the average income per ton of ternary batteries recycled using the wet recycling process is 18,073 yuan, and the average income per ton of lithium iron phosphate batteries recycled is 8,220 yuan. Therefore, using the wet recycling process, the profit will be 3,258 yuan for every 1 ton of ternary batteries recycled, and the loss will be 1,695 yuan for every 1 ton of lithium iron phosphate batteries recycled.

　　3.3 Fire recycling process

　　1) Fire recycling process

　　Fire recycling (high-temperature metallurgy) technology first requires automatic discharge treatment of batteries, then classification according to battery types, separation of metal shells and electrode material parts through vibration screening and magnetic separation, and placing the electrode material part into a dry electric arc furnace for high-temperature treatment , the carbon and organic matter in the electrode fragments will be burned away at high temperature, and reducing gas will be produced during combustion, which has a protective effect on the metal elements in the electrode. Finally, after screening, fine powdery materials containing metals and metal oxides are obtained. The process flow is, As shown.

　　It can be seen that the pyrometallurgical process is relatively simple and suitable for large-scale processing of various types of used lithium batteries. The battery material itself can provide a large amount of energy consumption required for incineration and can minimize the residual volume, but other components in the battery electrolyte and electrode The combustion of components can easily cause air pollution, and the pressure of incineration exhaust gas treatment is high [21].

　　Fire recycling process

　　According to literature reports, European companies Umicore [22, 23] and BARTEC recycle lithium-ion batteries through special ultra-high temperature furnaces to produce Co or Ni alloys and rare earth oxides, and graphite and organic solvents are used as fuel to release energy. The pyrometallurgical method is conducive to the processing of large amounts of used lithium batteries. Umicore's Hoboken plant in Antwerp, Belgium, is currently capable of processing up to 7,000 tons/year of used secondary batteries. Churl Kyoung Lee and others first crushed used lithium-ion batteries and then performed heat treatment to turn the flammable material into gas, leaving LiCoO2.

　　2) Economic analysis of fire recycling process

　　The pyrometallurgical recycling process requires high-temperature treatment of pretreated electrode materials in an electric arc furnace, and a large amount of waste gas and waste residue will be generated during the treatment process. Therefore, the cost of the pyrometallurgical recycling process mainly comes from raw material recycling, fuel power and Waste gas and waste residue treatment, etc.

　　Table 7 Treatment cost per ton of waste battery fire recycling process (yuan)

　　Through survey data, it can be seen that the average cost of processing 1t of ternary batteries in the fire recycling process is 14,390 yuan, and the average cost of processing 1t of lithium iron phosphate batteries is 9,490 yuan.

　　In addition, the main benefits of each material obtained by processing 1t of ternary batteries and lithium iron phosphate batteries using the fire recycling process are shown in Tables 9 and 10.

　　Table 9 Recycling efficiency and revenue of lithium iron phosphate battery fire recycling process

　　Table 10 Recycling efficiency and revenue of ternary material battery fire recycling process

　　From the above data, it can be concluded that the average income per ton of ternary batteries recycled using the fire recycling process is 1,705 yuan, and the average income per ton of lithium iron phosphate batteries recycled is 7,994 yuan. Therefore, using the fire recycling process, the profit will be 3,015 yuan for every 1 ton of ternary batteries recycled, and the loss will be 1,496 yuan for every 1 ton of lithium iron phosphate batteries recycled.

　　3.4 Biological recovery process

　　Biological method is another new research direction in the recycling of power lithium batteries. The bioleaching process uses microorganisms to convert insoluble substances into soluble substances, and takes certain measures to dissolve them, obtain preparations containing metal elements, and separate impurities from heavy metals, so that the purpose of recycling can be achieved. Compared with conventional battery recycling technology, the bioleaching process does not produce pollutants, is simple to operate, and has low investment. However, the bioleaching process is still in its infancy, and there are still a series of problems that have not yet been overcome, such as strain selection, strain cultivation, control of leaching conditions, etc. To realize the widespread application of the bioleaching process, in-depth research is required. Research.

　　3.4 Comparison of four recycling processes

　　Several basic technical routes for recycling power lithium batteries can be compared and evaluated from the aspects of process characteristics, energy efficiency and applicability, as shown in Table 1.

　　Table 3-1 Comparison of technical routes of several basic recycling and treatment processes for power lithium batteries

　　The chemical and physical recycling processes of used power lithium batteries have their own advantages and disadvantages, and the recycling objects are also different. Therefore, if the combined recycling process is optimized and adopted, the advantages of various basic processes can be brought into play, renewable resources and energy can be recovered as much as possible, and the economic benefits of recycling can be improved.

　　Used lithium battery 18650 combined recycling process flow chart

　　With reference to the ore processing process, Al-Thyabat S et al. proposed a joint recycling process for used lithium-ion batteries that combines pyrometallurgy, hydrometallurgy and physical separation as shown in Figure 3 to maximize the recovery of valuable resources. Georgi-Maschlera T and others also proposed a similar process to recover metal elements in lithium batteries, and obtain metal Co alloys by controlling the reduction atmosphere during incineration. Japan's Sony Corporation and Sumitomo Metal Mining Corporation are cooperating to study the technology of recovering cobalt and other materials from used lithium-ion secondary batteries. The process is to first incinerate the batteries, then screen to remove iron and copper, and then heat and dissolve the remaining powder in acid. Cobalt oxide can be extracted by extraction with organic solvents. Li Jinhui et al. proposed to separate the electrode materials in lithium batteries through physical pretreatment of crushing and ultrasonic cleaning, and then used acid to leach the Co element, thereby reducing the energy consumption and secondary pollution of recycling; Li Li et al. studied the use of physical disassembly Solution: The recycling process of N-methylpyrrolidone (NMP) and LiCoO2 in acid leaching anode materials has the advantage of simple equipment and can be applied to large-scale recycling. An Hongli et al. studied the process of recovering Mn and Li from used lithium manganese oxide batteries through discharge, disassembly, active material stripping and acid solution precipitation. The HNO3/H2O2 system was used to extract the process when the solid-liquid ratio was 65g/L. When lithium manganate is treated at 600°C, the manganese recovery rate reaches 98%, and the purity of the resulting Li2CO3 precipitation can reach more than 97%.

　　5 Summary

　　This chapter starts from the research progress of power lithium battery 18650 recycling technology and introduces two methods of power lithium battery 18650 recycling, namely cascade utilization and disassembly recycling. Cascade recycling can improve the energy utilization rate of power lithium batteries and reduce battery costs. Disassembly and recycling can recover waste metal and reduce the pollution of waste to the environment. Based on the above detailed introduction to the power lithium battery 18650 recycling process, the following conclusions can be drawn:

　　(1) The recycled retired power batteries can be used as a supplementary regulating power source for solar power generation and wind power generation, and can also be used for power grid peak regulation and mobile base station power supply.

　　(2) Disassembly and recycling is divided into physical recycling process, wet recycling process, fire recycling process and biological recycling process. Among them, wet recycling process is the most common and is also the current mainstream process for power lithium battery 18650 disassembly and recycling in my country.

　　(3) Taking lithium iron phosphate and ternary batteries, which currently have a large market share, as examples to analyze the economics of recycling power lithium batteries using different processes, it was found that no matter what process is used to recycle lithium iron phosphate batteries, there will be a loss. Yuanbao will make a profit.

　　(4) Comprehensive consideration of the advantages and disadvantages of physical recovery process, wet recovery process, fire recovery process, and biological recovery process, and the use of combined recovery process can give full play to the advantages of various basic processes and recover renewable resources and waste as much as possible. energy and improve the economic benefits of recycling.

　　(5) There is no particularly mature and universal recycling process. Therefore, the recycling technology of power lithium batteries is still in the process of continuous development and improvement.

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