Power lithium-ion battery recycling channels and key technology decomposition

my country's new energy vehicle processing will exceed the 1 million mark in 2018, and it will exceed 2 million in 2020, and the stock will exceed 5 million. 2015 is the first year for my country to promote the use of new energy. In 2018, the large-scale decommissioning of power lithium-ion batteries is about to start, and 2019 will enter an explosive period.



This article analyzes three aspects of knowledge: one is the seriousness of the environmental pollution of power lithium-ion batteries; the second is the economy of power lithium-ion battery recycling; the third is the critical technology of power lithium-ion battery recycling, and the impact on power lithium-ion batteries Recycling proposal.



1. The severity of environmental pollution caused by power lithium-ion batteries



After the large-scale decommissioning of lithium-ion power lithium-ion batteries, as waste materials, they must have an adverse effect on the environment and cause certain environmental pollution. Although lithium-ion power lithium-ion batteries do not contain mercury, cadmium, lead and other toxic heavy metal elements, and are relatively environmentally friendly compared to lead-acid batteries, the metal ions and negative electrodes of lithium-ion power lithium-ion batteries Carbon dust, strong alkalis in electrolytes, and heavy metal ions may cause heavy environmental pollution, including increasing the pH of the soil. The metal and electrolyte in lithium-ion batteries, such as cobalt, may cause intestinal disorders, deafness, and myocardial ischemia. At present, my country`s battery recycling capacity is limited, and most of the used batteries have not been effectively disposed of. At present, the most important solutions for used batteries are solidification and deep burying and storage in abandoned mines. If the scale is too large, it will cause damage to the natural environment. And potential threats to human health.



In a word, if the lithium-ion power lithium-ion battery is retired on a large scale, people must attach great importance to it, take it seriously, and solve it steadily.



2. The energy consumption of non-ferrous metal recycling and primary metal refining process is much smaller



According to data analysis, the uniform content of lithium in the ternary battery is 1.9%, nickel 12.1%, and cobalt 2.3%; in addition, the proportions of copper and aluminum have reached 13.3% and 12.7%. Cobalt has good ductility and ferromagnetism, high temperature resistance, corrosion resistance, and magnetic properties. It is widely used in aerospace, machinery manufacturing, electrical and electronic, chemical, ceramic and other industries. In 2015, the global output of cobalt ore was 123,800 tons, Congo (DRC) produced 63,000 tons of cobalt ore, accounting for more than 50%, and my country only produced 7,700 tons, accounting for 6.2%. For our country, cobalt is a scarce resource. Therefore, the recovery and reuse of cobalt from waste batteries is becoming more and more economical. Lithium is an important element in power lithium-ion batteries. Lithium resources are widely distributed in nature. However, the extraction process of lithium resources has higher barriers in the industry.



Due to the growing demand for new energy vehicles, more and more companies are beginning to pay attention to the recycling of lithium-ion batteries, and use batteries to recycle raw materials and process batteries. The energy saving rate is between 70% and 90%. Recycling raw materials and processing batteries through batteries has absolute advantages in terms of energy saving and emission reduction, and its macro-level economy is self-evident.



3. Decomposition of power lithium-ion battery recycling channels



After the power lithium-ion battery is retired from the car, its charge and discharge performance may not be able to meet the power demand of the vehicle, but the internal chemical composition of the battery has not changed. Related power supply base stations, street lights, low-speed electric vehicles, etc., are eliminated and finally enter the recycling system. In summary, it is divided into two cyclic processes:



①Echelon utilization:



The reduced battery capacity makes the battery unable to make the electric vehicle run normally, and it can still be used continuously in other ways, such as electricity storage. (Note: the battery itself has not been scrapped)



②Dismantling and recycling:



The battery cannot be used continuously because the battery capacity is severely depleted. The only way to recycle the battery is to recover valuable renewable resources.



The Chinese government clearly adopts the processor responsibility extension system, as shown in Figure (1). But the implementation of this system has not yet started. Recycling channels have not yet been established. This is a key issue that needs to be addressed urgently.



Currently there are channels:



①Recycling small workshop



The points are multifaceted, and the cost of recovery is low. However, these small workshops have no technical guarantees and are prone to security risks.



②Professional recycling company



With advanced technology and equipment, standardized process and strong comprehensive strength, it is the backbone company for the recycling and utilization of power lithium-ion batteries. But how to ensure that these companies are profitable? The market has not yet grown up, and how government policies must be implemented. In-depth research is needed.



③Association for Recycling of Waste Materials



The Waste Material Recycling Association has more member units, more contacts, and a more complete recycling network. But at present, such organizations have not yet launched the business of recycling power lithium-ion batteries. How to rationally deploy the power lithium-ion battery recycling market? How to regulate the management? There is still a lot of work to be done.



Fourth, the recycling process classification of waste lithium-ion batteries



According to the classification of different extraction processes, the recycling technology of lithium-ion batteries can be divided into three categories:



(1) Dry recycling technology



It mainly includes mechanical separation method and high temperature pyrolysis method (or called high temperature metallurgy method), see table (1). The dry recovery process is relatively short, and the recovery is not very specific. It is the preliminary stage to realize the separation and recovery of metals. The critical point refers to the straightforward recovery of materials or valuable metals without using media such as solutions. The critical point is to use physical separation and high-temperature pyrolysis methods to rupture the battery and perform coarse sieve classification, or high-temperature analysis to remove organic matter for further Element recycling.



(2) Wet recycling technology



The wet recycling technology process is more complicated, as shown in Table (2), but the recovery rate of each valuable metal is relatively high, and it is currently an urgent technology to solve waste nickel-hydrogen batteries and lithium-ion batteries. Wet recovery technology uses various acid and alkaline solutions as the transfer medium to transfer metal ions from the electrode material to the leaching solution, and then through ion exchange, precipitation, adsorption and other means, the metal ions are removed from the solution in the form of salts, oxides, etc. Extracted from it.



(3) Biological recycling technology:



At present, the research on biological recycling technology has just started, which is the ideal direction for the development of lithium-ion battery recycling technology in the future. Biological recycling technology has the characteristics of low cost, low pollution and reusability. The most important thing is to use microbial leaching to convert the useful part of the system into soluble compounds and selectively dissolve them to obtain a solution containing effective metals, to achieve the separation of the target part from the impurity part, and finally to recover valuable metals such as lithium.



The entire recovery process is generally divided into 4 parts: (1) pre-solving part; (2) electrode material repair; (3) valuable metal leaching; (4) chemical purification.



The first step: the pre-solving process, the purpose of which is to initially separate and recover the valuable parts of the old lithium-ion battery, and efficiently and selectively collect the high value-added parts such as electrode materials, so that the subsequent recovery process can proceed smoothly. The pre-solving process generally combines cracking, grinding, screening and physical separation methods.



The second step: material separation. In the pre-solving stage, the mixed electrode material of the positive electrode and the negative electrode is enriched. In order to separate and recover valuable metals such as Co and Li, the mixed electrode material must be selectively extracted. The material separation process can also be in accordance with dry recycling, wet recycling and biological recycling.



The third step: chemical purification. Its purpose is to separate, purify and recover various high value-added metals in the solution obtained in the leaching process.



Five, summary



① Lithium-ion batteries are more environmentally friendly than lead-acid batteries, but they also pollute the environment. Facing the large-scale decommissioning of power lithium-ion batteries, the basic ways of utilization are as follows: one is cascade utilization; the other is the resource utilization of waste lithium-ion batteries.



②The recycling technology of used lithium-ion batteries is mature, so there is no need to worry too much.



③Developing new energy vehicles, first is the measures taken by the Chinese government to deal with the increasing unsafeness of gasoline (diesel) oil; second, lithium-ion batteries are more environmentally friendly than lead-acid batteries; third, lithium-ion batteries There are mature technologies that can solve the environmental problems that arise.