Evaluating the cost and carbon footprint of second-life electric vehicle batteries in residential and utility-level applications.

The volume of end-of-life automotive batteries is increasing rapidly as a result of growing electric vehicle adoption. Most automotive lithium-ion batteries (LIBs) are recycled but could be repurposed as second-life batteries (SLBs) since they have 70-80% residual capacity, which can be adequate for stationary applications. SLBs have been proposed as potential, inexpensive, low-carbon energy storage for residential and utility-level applications, with or without photovoltaics (PV). However, it is unknown whether SLBs will be better than new batteries and whether SLBs will provide similar cost and carbon emission reduction for the different stationary applications in all locations. This work compared the levelized cost of electricity and life-cycle carbon emissions associated with using SLBs and new LIBs in the US for three energy storage applications: (1) residential energy storage with rooftop PV, (2) utility-level PV firming, and (3) utility-level peak-shaving, leading to a total of 41 scenarios. SLBs reduced the levelized cost of electricity by 12-57% and carbon emissions by 7-31% compared to new LIBs in the considered applications, with higher reductions for utility-level applications. SLBs still provided benefits at the residential level when compared to rooftop PV alone by reducing the levelized cost by 15-25% and carbon emissions by 22-51%, making SLBs attractive to residential consumers as well. SLBs offer an opportunity to utilize an end-of-life product for energy storage applications, provided the uncertainty in SLB quality and availability is addressed.

Economic and Environmental Feasibility of Second-Life Lithium-Ion Batteries as Fast-Charging Energy Storage.

Energy storage can reduce peak power consumption from the electricity grid and therefore the cost for fast-charging electric vehicles (EVs). It can also enable EV charging in areas where grid limitations would otherwise preclude it. To address both the need for a fast-charging infrastructure as well as management of end-of-life EV batteries, second-life battery (SLB)-based energy storage is proposed for EV fast-charging systems. The electricity grid-based fast-charging configuration was compared to lithium-ion SLB-based configurations in terms of economic cost and life cycle environmental impact in five U.S. cities. Compared to using new batteries, SLB reduced the levelized cost of electricity (LCOE) by 12-41% and the global warming potential (GWP) by 7-77%. Photovoltaics along with SLB reduced the use of grid electricity and provided higher GWP and cumulative energy demand (CED) reduction compared to only using SLB. The LCOE of the SLB-based configurations was sensitive to SLB cost, lifetime, efficiency, and discount rate, whereas the GWP and CED were affected by SLB lifetime, efficiency, and the required enclosure materials. Solar insolation and electricity pricing structures were key in determining the configuration, which was economically and environmentally suitable for a location.

Closed Loop Recycling of Electric Vehicle Batteries to Enable Ultra-high Quality Cathode Powder.

The lithium-ion battery (LIB) recycling market is becoming increasingly important because of the widespread use of LIBs in every aspect of our lives. Mobile devices and electric cars represent the largest application areas for LIBs. Vigorous innovation in these sectors is spurring continuous deployment of LIB powered devices, and consequently more and more LIBs will become waste as they approach end of life. Considering the significant economic and environmental impacts, recycling is not only necessary, but also urgent. The WPI group has successfully developed a closed-loop recycling process, and has previously demonstrated it on a relatively small scale 1 kg spent batteries per experiment. Here, we show that the closed-loop recycling process can be successfully scaled up to 30 kg of spent LIBs from electric vehicle recycling streams, and the recovered cathode powder shows similar (or better) performance to equivalent commercial powder when evaluated in both coin cells and single layer pouch cells. All of these results demonstrate the closed-loop recycling process has great adaptability and can be further developed into industrial scale.

Cradle-to-Gate Emissions from a Commercial Electric Vehicle Li-Ion Battery: A Comparative Analysis.

We report the first cradle-to-gate emissions assessment for a mass-produced battery in a commercial battery electric vehicle (BEV); the lithium-ion battery pack used in the Ford Focus BEV. The assessment was based on the bill of materials and primary data from the battery industry, that is, energy and materials input data from the battery cell and pack supplier. Cradle-to-gate greenhouse gas (GHG) emissions for the 24 kWh Ford Focus lithium-ion battery are 3.4 metric tonnes of CO2-eq (140 kg CO2-eq per kWh or 11 kg CO2-eq per kg of battery). Cell manufacturing is the key contributor accounting for 45% of the GHG emissions. We review published studies of GHG emissions associated with battery production to compare and contrast with our results. Extending the system boundary to include the entire vehicle we estimate a 39% increase in the cradle-to-gate GHG emissions of the Focus BEV compared to the Focus internal combustion engine vehicle (ICEV), which falls within the range of literature estimates of 27-63% increases for hypothetical nonproduction BEVs. Our results reduce the uncertainties associated with assessment of BEV battery production, serve to identify opportunities to reduce emissions, and confirm previous assessments that BEVs have great potential to reduce GHG emissions over the full life cycle and provide local emission free mobility.