How to deal with waste lithium batteries-separation technology of cathode materials

With the expansion of the application field of lithium batteries, the annual output of lithium batteries in my country is also increasing. In 2011 alone, the national output of lithium batteries reached 2.966 billion, a year-on-year increase of 18.22%. At present, my country has become a major country in the production, consumption and export of lithium batteries, and the number of old batteries discarded every year is also increasing. Improper disposal of these used batteries will bring about various environmental pollution problems. Waste lithium batteries contain a large amount of valuable metals, of which: cobalt is 5%-20%, lithium is 5%-7%, and nickel is 5%-10%[5]. Reasonable recovery of these valuable metals can not only It has economic benefits to alleviate the current shortage of resources in our country, and at the same time it can turn waste into treasure, which has significant social and environmental benefits.

Lithium battery structure

Lithium batteries are mainly composed of positive and negative electrodes, separators, electrolytes, and shells. Among them, the positive electrode material occupies an important position in the structure of the battery. At present, in commercial lithium batteries, the widely used cathode material is composed of 88% active material (LiCoO2) and 8% acetylene black conductive agent uniformly coated with 4% polyvinylidene fluoride (PVDF) binder It is composed on both sides of aluminum foil as a current collector. For the positive electrode material obtained after disassembly, the composition of the positive electrode material was analyzed and determined in this study. According to the structure of the positive electrode material, three methods of organic solvent dissolution, crushing and screening, and high temperature decomposition were used to enrich and separate the constituent materials, and analyzed The result of its separation can be further applied to the actual processing process.

Crushing and screening

The positive electrode of lithium battery is made of powdered active material lithium cobalt oxide and acetylene black conductive agent pasted on aluminum foil through PVDF binder. Taking into account the good ductility of aluminum foil, the powdered active material can be peeled from the aluminum foil by mechanical impact during the crushing process, and the lithium cobalt oxide powder and the aluminum foil can be screened and separated by the difference in shape and size between particles. The lithium battery cathode is crushed with a high-speed universal crusher, the crushed dissociated materials are screened, the content of cobalt, aluminum and other elements in different particle sizes are measured, and the crushing effect and the crushing and screening rules at different times are analyzed.

The crushing and screening technology can effectively crush and dissociate the cathode material of the waste lithium battery, and realize the separation and enrichment of the anode active material and the metal aluminum. In actual operation, subsequent sorting measures need to be added to improve the separation and recovery of lithium cobalt oxide active materials.