Sorting of Spent Electric Vehicle Batteries for Second Life Application

Electric vehicles (EV) typically have around 80% of their initial capacity at the end of the battery life. It is widely anticipated that these EV batteries will retain significant capacity remaining and potentially operate for additional years in their second life. Finding ways to repurpose the batteries in home, industrial and grid-scale energy storage system (ESS) is becoming more urgent. Establishing or verifying battery performance in comparison to these targets is a principal objective. Non-availability of onboard diagnostics data and accurate assessments of the automotive and second use battery degradation stand out in particular. This paper characterises the energy and power density of a cell using a hybrid pulse power characterisation (HPPC) test. Experimental results from five randomly selected cells from disassemble Nissan leaf pack that reach end of life (EoL) shows that all the cells satisfied the ESS performance targets of electric vehicle (EV) of 700 W/Kg, 300 W/Kg during discharge/regen respectively. The paper further proposes the used of HPPC micro cycle based on offline data for feature extraction to distinguish between power and energy density of the cell in 80 s, which is significantly quicker.