According to the China Automotive Technology Research Center, the cumulative scrap volume of power batteries in 2015 was around 20,000 to 40,000 tons. Around 2020, the cumulative scrap of power batteries for pure electric (including plug-in) passenger cars and hybrid passenger cars in China alone will reach a scale of 120,000 to 170,000 tons. However, the recycling rate of batteries in China is less than 2%, and the large number of discarded batteries has caused waste of resources and energy and environmental pollution.

According to the estimation of China Automotive Technology Research Center, the cumulative scrap volume of power batteries in 2015 is about 20,000 to 40,000 tons. Around 2020, the cumulative scrap volume of power batteries for pure electric (including plug-in) passenger cars and hybrid passenger cars in China will reach 120,000 to 170,000 tons. However, the recycling rate of batteries in China is less than 2%, and a large number of discarded batteries have caused waste of resources and energy and environmental pollution.

Power battery recycling technology and process

1. Composition of lithium-ion power batteries

Lithium batteries are mainly made up of several components such as positive electrode material, negative electrode material, electrolyte and diaphragm. The positive electrode is usually made by fixing the positive material to the electrode with the adhesive polyvinylidene fluoride (PVDF). The negative electrode is usually made of graphite structured carbon material, such as carbon/graphite insert material, which is made by mixing carbon material, acetylene black and binder in a certain ratio and coating it on copper foil. The diaphragm is mainly composed of polypropylene, polyethylene microporous film or a double layer of both, and its thickness is around 10 μm. The electrolyte is mainly an organic solvent containing a lithium salt, where the lithium salt is usually LiPF6, but LiClO4 or LiBF4 is also used. the organic solvent is usually a carbonate (dimethyl carbonate, vinyl carbonate, methyl carbonate, diethyl carbonate, etc.). The housings are stainless steel, nickel-plated steel or aluminium housings etc. The presence of these substances can make the indiscriminate disposal of used batteries cause water pollution, endangering the survival of aquatic life and the use of water resources. Electrolyte solutions such as waste acids and alkalis can acidify or alkalise the soil.

The specific material composition of lithium-ion batteries in some hybrid vehicles is shown in Table 2. It can be seen that used lithium-ion power batteries contain large amounts of lithium, nickel, manganese, iron and other elements. According to the results of the analysis in question, recycling lithium-ion batteries can save 51.3% of natural resources, including a 45.3% reduction in ore consumption and 57.2% in fossil energy. Therefore, if these valuable metals can be efficiently recovered from a large number of used lithium-ion batteries, it not only has a high economic value, but also can reduce the pollution to the environment.

2. Recycling technology for power batteries

Combined with circular economy theory and product life cycle analysis (LCA) principles to establish. According to the relevant USABC evaluation standards, the end of life of a power battery is when the actual capacity falls below 80% of the nominal capacity. Recycling this part of the battery for secondary use will greatly reduce the environmental pollution. Used power batteries that no longer have use value are recycled and remanufactured.

At present, the recycling process for used lithium-ion batteries at home and abroad is: firstly, the batteries are thoroughly discharged, then dismantled to separate out the positive electrode, negative electrode, electrolyte and diaphragm and other components. The electrode materials are then subjected to alkaline leaching, acid leaching and extraction after decontamination to achieve enrichment of valuable metals. The methods used in the recovery process can be divided into 3 main categories according to the extraction process: dry recovery technology, wet recovery technology and biological recovery technology.