IVL Swedish Environmental Research Institute

The nickel metal hydride (NiMH) battery technologyhas been designed for use in electric vehicles,solar-powered applications and power tools. Thesebatteries contain the critical and strategic rawmaterials cobalt, nickel and several rare earthelements (REE). When designing a battery recyclingprocess, there are several choices to be maderegarding end-products and process chemicals. Theaim of this study is to investigate and comparethe environmental and economic sustainability ofdifferent recycling options for NiMH batteriesby taking projected market developments intoconsideration and by applying life cycle assessmentand life cycle costing methods. The comparativestudy is limited to recovery of the REEs. Twohydrometallurgical processes for recovery of theREEs from the anode material are compared withextraction of REEs from primary sources in China.The processes compared are a high-temperaturesulfation roasting process and a process based onhydrochloric acid leaching followed by precipitationof REE oxalates. By comparing the different recyclingapproaches, the hydrochloric acid process performsbest. However, the use of oxalic acid has alarge impact on the overall sustainability footprint.For the sulfation roasting process, the energy,sodium hydroxide and sulphuric acid consumptioncontribute most to the total environmental footprint.