Method for Recycling Used Li-Ion Batteries to Build Battery Packs with Specific Output Parameters: A Case Study of the 4s6p Battery Pack

This paper proposes an original method for selecting cylindrical Li-Ion cells in the popular 18650 format, sourced from the disassembly of laptop batteries, for reuse and to give them a second life. The Introduction analyzes the key properties of Li-Ion cells in comparison with other solutions, with a particular focus on the latest battery technologies based on Na-Ion cells, which are built using less expensive sodium. The work involved disassembling damaged batteries, followed by an initial selection of cells based on voltage and internal resistance measurements. A key part of the work was developing a simulation based on a random arrangement of cells in a 4s6p pack and identifying the optimal configuration based on three established criteria. Finally, a prototype battery was constructed, and its discharge curves were analyzed at three constant power levels ranging from 50 W to 150 W. In conclusion, it was found that the developed method is of significant importance from an environmental protection perspective and can be applied to the construction of other battery packs using various Li-Ion cells; the optimal load level for the tested prototype in the case study was a constant load of 50 W.