Quantifying the energy withdrawn from the lithium-ion battery during electrochemical discharge

The rising demand for electric vehicles (EVs) has led to an increased demand for lithium-ion batteries (LIBs). Due to the limited natural sources of battery materials, the need for safe and efficient recycling of LIBs is critical. Batteries at their end-of-life still might have residual energy. Therefore, safe discharge of batteries prior to recycling is needed to minimize the risk of explosion and thermal runaway. This study investigates the electrochemical discharge of LIBs by sodium chloride (NaCl) and potassium carbonate (K₂CO₃) solutions, with a focus on the impact of discharge current. A novel methodology enables the real-time monitoring of the voltage and current of the battery during electrochemical discharge. This, in turn, can be used to optimize the discharge process for safe and efficient recycling. The results reveal that K₂CO₃ outperforms the traditionally preferred NaCl electrolyte, providing a higher energy recovery in a shorter time despite retaining higher steady-state voltages (around 76% when 20 wt% K₂CO₃ was used as a discharge medium). Additionally, an excessive discharge current can lead to overheating and a higher voltage rebound. This should be considered when optimizing the electrochemical discharge process. By balancing the discharge rate, discharge time, and energy recovery, this study provides tools to increase the sustainability and safety of LIB preprocessing before recycling. ● Batteries at the end-of-life might be hazardous due to their remnant energy. ● Aqueous K₂CO₃ electrolyte provides for optimizing energy recovery from the battery. ● Higher electrolyte concentrations increase the initial discharge current. ● In 20 wt% K₂CO₃ electrolyte, over 76% of the energy in the battery was recovered. ● K₂CO₃ was able to recover more energy despite having a higher final voltage.