What is the use of recycling lithium batteries?

With the more and more widespread application of lithium-ion batteries, the recovery of valuable metals in lithium-ion batteries, the reduction of environmental pollution, and the alleviation of resource scarcity are of great social and economic significance.

Waste batteries contain a large amount of heavy metals and electrolyte solutions such as waste acid and soda. If discarded at will, heavy metals that exude from waste batteries will cause pollution of rivers, rivers, lakes, and seas, indirectly threatening human health. Therefore, the recycling and disposal of waste batteries not only deals with pollution sources, but also realizes the recycling and reuse of resources.

At present, power cells are mainly nickel-metal hydride batteries and lithium batteries. Hybrid batteries currently use nickel-metal hydride materials. However, because some of the technical properties of nickel-metal hydride batteries are already close to the theoretical limit, they are not considered to be the future development direction. Relatively speaking, lithium-ion batteries have been widely recognized for their high working voltage, small size, no memory effect, small self-discharge, and long cycle life. Waste lithium ion batteries usually contain cobalt 5 % to 15 %, lithium 2 % to 7 %, and nickel 0.5 % to 2 %, and their recycling value is relatively high. Lithium-ion batteries also contain toxic substances such as lithium hexafluorophosphate, which can cause serious pollution to the environment and the ecosystem. Heavy metals such as cobalt, manganese, and copper can also be harmful to humans through the accumulation of biological chains. With the more and more widespread application of lithium-ion batteries, the recovery of valuable metals in lithium-ion batteries, the reduction of environmental pollution, and the alleviation of resource scarcity are of great social and economic significance.

1 Valuable metal recovery technology for used lithium ion batteries

1.1 Dry technology

Dry method is to reduce the lithium-ion battery roasting to separate cobalt and aluminum, leaching and separation of cobalt and acetylene black.

Japan's Sony Corporation and Sumitomo Metal Mine Co., Ltd. cooperated to study the technology of recovering cobalt from used lithium ion secondary batteries. The process was to burn the batteries first, then screen the iron and copper, and then heat the residual powder and dissolve it in acid. Cobalt oxide can be proposed with organic solvent extraction[ 2] And ...

Curl KyoungLee et al.[ 3] The waste lithium ion battery is first broken and then heated to turn the combustible material into gas, leaving LiCoO2. In the constant temperature bath, nitric acid and hydrogen peroxide are added to dissolve LiCoO2, making the leaching rate of Co and Li reach 85 %.

The dry process is relatively simple, but the energy consumption is high, and the combustion of electrolyte solution and other components in the electrode is likely to cause atmospheric pollution.

1.2 Wet technology

The wet method is to use inorganic acid solution to leach each valuable component in the waste battery and then recycle it in a certain way.

Leaching of lithium-ion secondary batteries with hydrochloric acid at 80 °C has leaching rates greater than 99 % for Co and Li, followed by extraction of Co with PC-288A(2-ethylhexophosphate-mono-2-ethylhexyl ether), Cobalt was recovered in the form of cobalt sulfate after reverse extraction. Then add sodium carbonate solution to form lithium carbonate precipitate, the recovery rate is close to 80 %.

Kudo Misthiko, etc.[ 5] Leaching lithium ion battery positive waste with acid, adding amphoteric metal to the leaching solution, making Co2 + Co, and then removing amphoteric metal to obtain metal Co.

Wangxiaofeng 6] The electrode material is first dissolved in dilute hydrochloric acid, then the pH = 4 is adjusted, the hydroxide of aluminum is selectively precipitated, and then the pH is adjusted to about 10, so that cobalt and nickel form ammonia complexes, and then O2 to Co2 +, Ni2 + oxidation, The solution is passed through the ion exchange resin, and Co and Ni are precipitated with oxalate.

Wufang[ 7] Alkali dissolved battery material is used to remove about 90 % of aluminum in advance, and then the H2SO4 + H2O2 system is used to leach filter slag. The leached filter contains impurities such as Fe2 +, Ca2 +, and Mn2 +. The mixture of cobalt and lithium was extracted with P204 solvent, and then cobalt and lithium were separated with P507 solvent extraction. Cobalt sulfate was obtained after reverse extraction, and lithium carbonate was recovered by precipitation. The primary recovery rate of lithium was 76.5 %.

Wet process energy consumption is also large, and the process flow is long, the equipment requirements are high, the cost is high, and the resource recovery rate is low.

1.3 Ion screening for lithium ion batteries

In 2003, Wuhan University of Technology invented a new method for the separation and recovery of lithium from waste lithium ion batteries using lambd-Mn O2 ion sieves, and was granted an invention patent that year. The steps are: disintegrate the battery and remove the shell, soak the battery core in hydrochloric acid to fully dissolve it; PH & GT of regulating system; 10, after filtration to obtain a liquid containing lithium ions; The lithium ion adsorbed in the ion sieve was selectively adsorbed and separated by the phosphati-Mn O2 ion sieve. Then the lithium ion adsorbed in the ion sieve was eluted with hydrochloric acid, the lithium chloride was obtained by evaporation elution, and Na2CO3 was added to the eluent. After heating and concentration, lithium carbonate precipitation was obtained[ 7] And ...

1.4 Biological leaching process

The so-called microbial leaching process is the use of microorganisms to convert useful components in the system into soluble compounds and selectively dissolve them to obtain metal-containing solutions, achieve the separation of target components from impurity components, and eventually recover useful metals[ 8] And ...

Compared with traditional battery recycling technology, bioleaching has the advantages of less investment in infrastructure, lower operating costs, and less pollution to the environment. However, this is a relatively new topic, and there are many problems that need to be solved, such as the selection and cultivation of strains, the control of leaching conditions, and the biological leaching mechanism of metals.

1.5 Other renewable technologies

The LiCoO2 electrode can be reduced to Co2 + by electrochemical reduction technology, while lithium is released from the solid structure of LiCoO2, which avoids the introduction of other chemical substances and complicates the subsequent processing process[ 9] And ...

D. -S. Kim et al.[ 10] According to the mechanism of "dissolvation-precipitation", the exploration of LiCoO2 repair and separation was carried out, and the LiCoO2 material was repaired and separated at the same time, and the method was simple.

2 Countermeasures and suggestions for recycling waste lithium batteries

2.1 Start with battery producers for sorting and recycling

Battery producers should mark batteries containing hazardous waste to indicate the type and content of hazardous substances for recycling purposes, while producers should continuously improve the battery production process and reduce the content of harmful components such as heavy metals in batteries.

2.2 Increased advocacy to promote environmental protection and awareness

At present, people's knowledge of waste battery pollution is not enough, and they have not yet formed the consciousness of environmental protection of collecting waste batteries. Although the recycling of used batteries has attracted the attention of relevant departments in recent years, designated designated units for recycling, but with little effect. Therefore, should

Great publicity to raise people's awareness of the significance of recycling waste batteries, relevant groups and organizations should also carry out corresponding practical activities to cultivate people's sense of social responsibility for protecting the environment, and form a good environmental protection atmosphere in the whole society.

2.3 Improvement of laws and regulations and establishment of a sound management system

In order to achieve low Mercury and mercury-free battery products, China has developed a "mercury-free dry battery" standard for battery management policies, and relevant ministries have issued a "Regulation on Limiting Battery Mercury Content". These regulations play a role in controlling the environmental pollution of waste batteries at the source. The relevant departments of the government should also formulate administrative measures and specific and feasible implementation rules that meet China's National conditions. Through legislation, producers and sellers are required to recycle their product waste. At the same time, a sound recycling system is established as soon as possible to create various convenient conditions for the recycling of used batteries.

2.4 Enhanced technical research and development

We need to increase research on the application of recycling technology for used batteries, and develop new technologies that have low investment, low pollution, and high efficiency in treatment. At the same time, control the content of harmful components from the source of battery production, accelerate the development of environmentally friendly rechargeable batteries, and reduce the amount of battery waste.

In the future, the resource technology of waste lithium ion batteries will be more comprehensive and mature. We should strengthen the environmental management of waste batteries, so that the treatment technology will be developed in the direction of low cost and no secondary pollution. At the same time, we will develop new types of green and environmentally friendly batteries, so that production and recycling can form a virtuous circle, which is truly beneficial to the people, harmless to the people, and harmless to nature.

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