As a crucial component of the waste lithium battery recycling system, the pretreatment of battery holder shrapnel requires a multi-stage coordinated operation to ensure safe and efficient resource recovery before recycling. This process encompasses a complete chain from initial treatment to deep purification, with the core objectives of eliminating safety hazards, separating impurities, and improving material purity to provide high-quality raw materials for subsequent recycling processes.
The first step in pretreatment is deep discharge and safe deactivation. Waste battery holder shrapnel may retain residual charge; direct disassembly could easily cause short circuits, fires, or electrolyte evaporation and explosions. In practice, small batches of fragments often use a brine soaking method to accelerate charge neutralization through the electrolyte solution; large-scale processing relies on specialized discharge equipment to reduce the voltage to a safe range with a constant current. During this stage, strict monitoring of temperature and voltage changes is necessary to prevent equipment damage or personnel injury due to excessive energy release.
Crushing and physical sorting are the core steps of pretreatment. After being processed by a specialized crusher, the battery holder shrapnel's outer shell, electrode plates, separator, and other components are initially separated. During the crushing process, nitrogen protection or a negative pressure environment is required to prevent the electrolyte from evaporating and forming flammable gases. Subsequently, physical methods such as magnetic separation, air separation, and gravity separation are used to further separate ferromagnetic materials, lightweight diaphragms, and denser metal particles. For example, conductive materials such as copper and aluminum, due to their density differences, can be efficiently separated using a gravity separator, while plastic components such as diaphragms are recovered through airflow separation.
For the separation of positive and negative electrode active materials, chemical or mechanical auxiliary processes are required. Negative electrode materials often use water-soluble binders; simply placing the fragments in an aqueous solution and stirring achieves the separation of graphite and copper foil. Positive electrode materials, due to the use of strong binders such as PVDF, require pyrolysis or chemical dissolution to break down the binder layer. Pyrolysis decomposes organic matter at high temperatures, causing the active material to detach from the aluminum foil surface; chemical methods use specific solvents to dissolve the binder, followed by filtration and washing to obtain pure positive electrode powder. This stage requires strict control of temperature and solvent usage to avoid introducing new impurities or damaging the material structure.
The recovery of electrolyte and organic solvents is an important supplement to the pretreatment process. The electrolyte volatilized during the crushing process contains harmful substances such as lithium hexafluorophosphate, which must be rendered harmless through condensation recovery or combustion. Some processes employ low-temperature distillation technology to separate organic solvents and lithium salts from the electrolyte; the former can be recycled for battery manufacturing, while the latter is purified and reintroduced into the supply chain. For electrolyte residues remaining in the fragments, multiple washing and neutralization processes are required to ensure their content is below safety standards.
Impurity removal and surface purification are crucial for improving material purity. Separated metal powders may be adhered to organic residues or oxide layers, requiring acid washing, alkaline washing, or ultrasonic cleaning to remove surface contaminants. For example, copper powder can have its surface oxides dissolved by dilute sulfuric acid treatment, followed by filtration and drying to obtain high-purity metal; graphite powder needs to be calcined at high temperatures to remove residual binders and moisture, restoring its conductivity. Strict control of the cleaning solution concentration and treatment time is necessary at this stage to avoid excessive corrosion leading to material loss.
Comprehensive environmental protection measures are required throughout the pretreatment process. Waste gas generated during crushing and pyrolysis contains volatile organic compounds and dust, which must be purified through activated carbon adsorption and catalytic combustion before discharge. Wastewater requires neutralization and precipitation to ensure that heavy metal and pH levels meet standards. Furthermore, operators must wear protective equipment and work in well-ventilated environments to avoid contact with harmful substances such as electrolytes.
The pretreatment of battery holder shrapnel serves as a bridge between used batteries and renewable resources. Through six key stages—deep discharge, crushing and sorting, active material separation, electrolyte recovery, impurity purification, and environmentally friendly treatment—efficient resource recovery of battery holder shrapnel can be achieved. This process not only reduces the environmental impact of waste but also provides technological support for the recycling of scarce metals such as lithium, cobalt, and nickel, promoting the transformation of the new energy industry towards a green and sustainable direction.
