Exploration of recovery technology of lithium battery materials

Författare: Iflowpower – Leverantör av bärbar kraftverk

First, outline the lithium-ion battery due to its excellent use performance such as high voltage, large capacity, no memory effect, etc. Lithium-ion batteries have now gone to every corner of our work and life, can be said to be everywhere, mobile phone, computer, camera, charging treasure, electric bicycle, new energy car, etc. At present, the total consumption of total lithium-ion batteries in the country is about 7.

8 billion. At present, my country's total mobile phone has exceeded 2 billion. Piece.

This does not include lithium-ion batteries used in common equipment such as laptops, cameras, charging treasures. With the increasing popularity of new energy vehicles, the use of lithium-ion batteries in new energy vehicles will drive the production of lithium-ion batteries. From mobile to electric bicycles to electric cars, there are more and more waste lithium ion batteries in life, but the resources are more tight, and environmental protection requirements are increasingly strict.

If there are countless waste lithium ion batteries, people Physical health will be injured directly or indirectly. The mobile phone lithium-ion battery will have a drum phenomenon for a long time. It may be damaged after external force.

The battery contains unstable electrolyte solution, and the leak will pollute the environment. Its electrolyte hexafluorophosphate (LiPF6) decomposes to generate harmful substances in humid air, while carbonate organic solvents will cause severe pollution on water, atmosphere and soil, and serious hazardous ecosystems. Even if the waste lithium battery does not have a damage, if it is lifted with the garbage, it is long long, the exudative heavy metal cobalt, copper, etc.

also constitutes potential pollution. Data show that 1 20G waste mobile phone lithium battery can pollute 6000m3 water resources, polluting 1km2 land for about 50 years. It can be seen that if you will dispose of hundreds of billions of mobile phone waste batteries and garbage, the pollution caused by the human environment can imagine.

In fact, the waste lithium battery can be recycled, such as some value heavy metal very recycled. Typically, the ratio of cobalt, lithium, nickel in waste lithium ion batteries is 5% to 15%, 2% - 7%, 0.5% - 2%, and these metals are one resource.

In particular, metal cobalt, because there is no separate deposit, mostly in copper, nickel mine, and the taste is low, so it is very rare, the price is more expensive, if it is effective recycling, it can alleviate the shortage of cobalt resources in my country. In addition, there is also a metal element such as copper, aluminum and iron in the waste lithium battery, which can be recycled and reused. It realizes the use of things, turning waste into treasure, not only environmental benefits, but also economic benefits objective.

Waste lithium battery recovery treatment helps to form a circular chain of "production-recycling-reproduction", solve the problem of waste lithium battery pollution and waste utilization, to achieve the sustainable development of new energy vehicles, alleviate my country's strategic metal resource shortage. Second, lithium ion battery recovery treatment technology The lithium ion battery consists of a positive electrode, a negative electrode, an electrolyte, a diaphragm, a current collector, a housing, and the like. After uniformly mixing the positive material, conductive agent, and organic adhesive of the battery, apply a negative electrode material, a conductive agent, an organic adhesive, and apply a negative electrode material, a conductive agent, and an organic adhesive.

The diaphragm is separated from the organic electrolyte, and finally wrapped with a housing. The waste lithium-ion battery must be completely discharged before recycling. Make sure that the person is not damaged, remove the outer casing, separating the electrode positive, negative material, collective fluid, electrolyte, etc.

, and then carry out the next recycling. 1. Recycling of lithium-ion battery housing with steel shell (square type), aluminum shell, nickel plated iron shell (cylindrical battery), aluminum plastic film (soft package), etc.

, as well as a battery cap, ie Battery positive and negative lead. The recycled lithium battery needs to be disassembled before the waste lithium battery needs to be disassembled, and the disassembled plastic and iron housing can be recovered. Usually: mechanical crushing and sieving method, that is, by mechanical crushing, sieving, sieving housing material; manual disassembly, considering that this method is not used as much as possible; low temperature refrigeration after disassembly, this process Technology is very environmentally friendly, but only part of the metal material and lithium salt can be recovered, the recovery efficiency is low, and it is impossible to achieve effective recovery of plastics.

2. Recycling of the positive electrode material is a positive electrode in a lithium-containing compound, only lithium ions, no metal lithium. Typically there is a material such as lithium manganate, lithium cobaltate, lithium iron phosphate, and nickel-cobalt-manganese acid, the active substance of most of the lithium ion battery positive electrode is still lithium cobaltate, and lithium manganganate is bonded by lithium nickel-cobalt-manganese acid.

And the advantages of the material of lithium cobaltate attracted the interest of many researchers, as the power battery of electric bicycles and electric vehicles. With the exhaustion of this non-renewable mineral resource, the positive material is 40% of the total battery total cost, if a heavy metal such as cobalt, nickel, lithium in the positive electrode material is effectively recovered, turned waste into treasure, and realizes the recycling of materials, Can ease the crisis of mineral resources and achieve sustainable development, while will also bring huge economic benefits. (1) The separation of the active material and the current collector must first effectively separate the positive electrode active material to the conductive concentrate aluminum foil, in order to achieve the recovery of the positive material, the current common method is: 1 blade.

Directly scrape the positive electrode material from the aluminum foil, the method will blow the aluminum foil to the fluid, resulting in collective debris, making the positive electrode active substance with the aluminum foil together difficult to separate. 2 high temperature incineration. The organic adhesive is removed by high temperature decomposition, separating the lithium battery composition material, oxidation, reduction and decomposition of the metal and its compound in the battery.

After volatilizing the vapor form, condensation collection. 3 organic solvent dissolution. According to the principle of the organic matter dissolved the organic matter, the organic adhesive polyvinylidene fluoride (PVDF) in the positive electrode material is dissolved in a suitable organic solvent, thereby peeling the active substance from the aluminum foil.

Current research, more organic solvents - N-methylpyrrolidone (NMP), experimentally proved that NMP soaking treatment of the positive electrode cobalt lithium film at 70 ° C can completely peeled off the active material, and the metal form of the aluminum foil does not change directly. The use of the organic solvent after use can remove the binder by distillation to achieve recycling, the only disadvantage is that the NMP price is too expensive about 30,000 yuan / t, and the cost of high cost makes it limit. 4 electrolysis stripping.

Separation of battery positive material and aluminum foil fluid by electrolysis process. The positive electrode of the waste lithium battery is extremely cathode, lead is an anode, and the dilute sulfuric acid solution having citric acid is an electrolytic solution, and electrolysis is electrolyte at a certain current density, and the active substance falls off from the aluminum foil to the solution, filtered to obtain an electrolysis Liquid and battery slag. Cobalt has a leaching rate of 50% under low acidity conditions, and the current efficiency is more than 70%.

(2) Recycling of the active substance is immersed: the separated positive electrode active material is leached in the system of sulfuric acid and hydrogen peroxide to obtain CO2 + and Li +, and then the leaching liquid containing CO2 + and Li + first uses two (2-ethylhexyl) ) The phosphate (P2O4) extractant removes the impurity ions therein, and then extracts cobalt ions in the separated water phase with ethylhexyl phosphoric acid mono-2-ethylhexyl (P5O7) extractant. 2 alkali leaching: When electrolysis is peeled off the positive electrode active material, the aluminum of the surface layer occurs, and a dense oxide film is generated, and aluminum ions are generated, and the aluminum ion has toxic, so that aluminum effect is removed. If you don't want to have an impact on the separation effect.

The first alkaline is subjected to cobalt and lithium. The best conditions for alkaline immersion recovery aluminum are: temperature 90 ° C, 10% sodium hydroxide (NaOH) solution, aluminum recovery reaches 96%; the best conditions for acid-soluble recovery cobalt, lithium is: temperature 90 ° C, 4 mol / L sulfuric acid solution, solid-liquid ratio 1: 8, reaction time is 100 min, cobalt, lithium leaching rate reaches 92%. This method can recover the valuable metal in the waste, the process flow is simple, and there is a practical value for the environment without secondary pollution.

3 use biomass straw sulfuric acid system to leach the residue, cobalt leaching rate reaches 99%. And through the level 2, 3 leaching process, the acid and organic contaminants (COD) in the leaching liquid are fully utilized. The leached cobalt uses oxalic acid precipitation, and the prepared battery material has good discharge performance [7].

4 directly generate a positive material by chemical reaction. The above methods are separated by aluminum and cobalt first. To obtain a positive material, further synthesis is required, the process is complicated, high cost.

If the positive material is directly synthesized during the separation, the production process can be greatly simplified to improve economic benefits. The positive electrode material in the waste smear is only degraded during the use of the structure, and as long as the adjustment is adjusted after effective separation, it can be reused. Directly integrated use of a waste-free metal, nickel, cobalt, manganese, etc.

, no need to separate elements such as nickel, cobalt, manganese, and lithium, and save raw material costs without elements such as nickel, cobalt, manganese, and lithium. 3. Recycling of the negative electrode material has a wide variety of the negative electrode materials: 1 metal material, such as lithium metal.

2 inorganic non-metallic materials, mainly carbon materials, silicon materials and other non-metallic composites. 3 transition metal oxide. Currently, more applications are carbon, graphite and non-graphite carbon materials.

Lithium titanate has a very excellent cycle life, safety and magnification performance, as can be used as a negative electrode material in electric vehicles, and the main disadvantage is to reduce the energy density of the battery. There are also some companies to develop tin alloy as an negative electrode material, but still in the research stage, less application. The conductive collector uses an electrolytic copper foil having a thickness of 7 to 15 μm, so it can be recovered in which the copper (content of about 35%) is recovered, and an additive for adhering to its plastic, rubber or the like can also be recovered.

Therefore, first, it is necessary to effectively separate the waste lithium battery negative electrode, maximize resource utilization of waste lithium battery. The mutual peeling between the toner and the copper foil is effectively realized by hammers, and then the copper foil and toner is initially separated according to a vibration sieve of the particle size difference and the difference in shape. The copper foil is enriched in a grain range greater than 0.

250 mm, and the carbon powder is enriched in less than 0.125 mm. It can be directly recovered according to different particle diameters.

For crushing particles having a particle size of 0.125 to 0.250 mm, the effective separation of copper and toner is achieved by air flow separation.

By hammering, the vibration screening and airflow sorting combination process can realize the resource utilization of metal copper and toner in the negative electrode material of waste lithium battery. 4. Recycling of organic electrolyte and diaphragm for digital waste lithium ion battery electrolytes do not recycle, usually use fire to burn it; and a lithium ion battery as a power supply is about 15% of the battery cost, With rich lithium ions, recycling is high.

Moreover, the currently used electrolyte is generally selected from the carbonate organic solution of LiPF6. In moist air, the LiPF6 will react to the hydrogen fluoride, which can be seen that effective recovering electrolyte not only reduces harmful gas emissions, but also has certain economic benefit. The diaphragm of the lithium battery has a microporous structure, and electrons can be prohibited from freely passing the lithium ion, a portion of the electrolyte is dispersed in the void of the electrode and the diaphragm, so the diaphragm is recovered.

The electrode, the separator is soaked in a suitable solvent for a certain period of time, the electrolyte will completely discharge into the solvent. Polycarbonate (PC) relative dielectric constant is large, which is advantageous for dissolution of lithium salts. Tongdong, Lai Qiong, Ji Xiao, etc.

A Canadian company has reducing the relative activity of each component in the electrolyte by low temperature technique, and then in the electrolytic solution in electrolyte with NaOH solution, the recovery treatment of lithium battery electrolyte is achieved. Third, the difficulties faced by lithium battery recovery 1. People's awareness of waste lithium battery recovery is weak, most people do not know how to dispose, the government has not established a special recycling institution, leading to a large number of lithium batteries Garbage is buried; on the other hand, there is enough recovery of waste lithium batteries to have a reuse value.

The government agency needs to promote the meaning of the recycling of lithium batteries to wake up the recovery of the people, lay the recycling network, and form a waste lithium battery. Recycling system. 2.

Recycling of waste lithium battery is complex, and after the high-waste lithium battery is split, it needs to be recovered by multiple processes. Therefore, this is a business, and there is no business. Willing to do.

There is currently no related policies to support the recovery of lithium batteries, and there is no significant impact on the environment. 3. The government has not enough policy and regulatory support.

At present, the recycling of lithium-ion batteries is basically in the company, and has not yet become climate, power lithium battery recovery, dismantling industrial norms, recycling channel standardization, scale, with the expansion of industrial scale, still need to be further improved. IV. Overview With the development of technology, lithium batteries have improved significantly in safety and service life, but the recycling of lithium batteries does not keep up with the pace.

With the comprehensive climbing of new energy vehicles, the lithium-ion battery will not be available. Some experts predicted that the waste dynamic lithium battery recycling market will begin in 2018. The scale of recycling markets after 3-5 years will be further crazy, so the establishment of special recycling institutions recycled the dynamic lithium-ion battery has been imminent.

In summary, the sustainable development of lithium batteries is closely related to the relationship between energy crises, ecological environment, energy saving and emission reduction, and profit-like people have a huge role in industrial development. New material industry.