Efficient and safe recycling of lithium-ion batteries can alleviate the concerns about the security of the raw material supply chains and the related economic, environmental, and ethical issues. However, previous research (1) has shown that the safety of aged and end-of-life lithium-ion batteries and cells is not yet sufficiently understood. Moreover, lithium-ion batteries misplaced in regular trash or mixed with other recyclable waste have caused multiple fires and millions of dollars in damages in recycling and waste management facilities when the batteries are accidentally crushed or punctured leading to the uncontrolled release of the residual energy in the batteries. (2)

Fully discharging or neutralizing any stored charge in the batteries at end of life can improve the safety of the recycling processes as well as in the transportation of the used batteries to the recycling facilities. However, discharging batteries individually can add significant costs to the process. Immersing the battery in a salt solution has been suggested as an easy and low-cost method to discharge the residual energy. In this work, a study was carried out on calendar aged commercial cylindrical cells and pouch cells immersed in solutions of different salts (NaCl, NaHCO₃ and Na₂CO₃) at varying concentrations to find out the most effective combination. NaCl solutions caused severe corrosion of the positive terminals of both cell types, which hindered the discharge process of the pouch cells due to the loss of electrical contact. Methods to enhance pouch cell discharge were tested. It was also studied if the corrosion can be utilized to ease the disassembling of the cell cases for recycling purposes.

References

1. Y. Preger, L. Torres-Castro, T. Rauhala and J. Jeevarajan, Journal of The Electrochemical Society, 169, 030507 (2022).
2. United States Environmental Protection Agency, An Analysis of Lithium-Ion Battery Fires in Waste Management and Recycling, Report number EPA 530-R-21-002, 2021, https://www.epa.gov/system/files/documents/2021-08/lithium-ion-battery-report-update-7.01_508.pdf