This study provides an analysis of the technological barriers for all-electric vehicles, either based on batteries (BEVs) or on H 2 -powered proton exchange membrane (PEM) fuel cells (FCEVs). After an initial comparison of the two technologies, we examine the likely limits for lithium ion batteries for BEV applications, and compare the projected cell-and system-level energy densities with those which could be expected from lithium-air and lithium-sulfur batteries. Subsequently, we will review the current development status of H 2 PEM fuel cells, with particular attention to their viability with regards to the required amount of platinum and the resulting cost and availability constraints. It is widely accepted that global warming is caused by CO 2 emissions and that they must be substantially reduced in order to prevent climate change. Since ≈23% of the world-wide CO 2 emissions are due to transportation, ≈75% of which are contributed by the road sector (numbers from 2012 1 ), a reduction of CO 2 emissions from vehicles is imperative to combat global warming. Towards this goal, many countries have passed legislature to lower passenger vehicle emissions over the long term like, e.g., the European Union mandate for 95 g CO2 /km fleet average emissions by 2020.2 The analysis by Eberle et al. 3 in Figure 1 suggests that this rather ambitious goal can only be met by means of extended range electric vehicles or all-electric vehicles in combination with the integration of renewable energy (e.g., wind and solar). Without increased integration of renewable energy sources and basing the calculations on the current European electricity generation mix, the only vehicle concept which could meet the 95 g CO2 /km target are pure battery electric vehicles (BEV100 in Fig. 1). However, for electricity produced entirely by renewable energy sources, the 95 g CO2 /km target could also be met by extended range electric vehicles with 40 miles all-electric range (E-REV40 in Fig. 1), if 50% of driving is powered by the battery (i.e., the average driving range would have to be below 80 miles), or by fuel cell electric vehicles (FECVs), with hydrogen produced by water electrolysis. While these propulsion concepts look promising, their contribution to CO 2 emission savings in the transportation sector would only be meaningful if their market penetration were substantial. In the absence of government regulations, the latter largely hinges on consumer acceptance, which in turn strongly depends on cost. In addition, in the case of BEVs, recent studies clearly showed that BEV driving range (closely followed by cost) are the predominant variables determining consumer acceptance. 4 In the following we will thus focus on the two vehicle types, which would be capable to meet and exceed the CO 2 emission targets of 95 g CO2 /km on the long-term, viz., pure BEVs and hydrogen powered FCEVs. For both vehicle types, but particularly for the latter, meaningful CO 2 emission reductions require the predominant use of renewable energy, which in turn necess...

On page A2610, left column, the first sentence after the subheading Lithium-sulfur battery concept.-should be Due to the high specific energy of the sulfur cathode (1675 mAh/g S ), lithium-sulfur batteries have also been considered as promising post-LiB technology with substantial gravimetric energy density and cost advantages over LiBs.On pages A2610, right column, first paragraph, the sentence that continues onto page A2611 and remainder of the paragraph should beThe third strategy is to use silicon based anodes instead of metallic lithium anodes (see Fig. 6c), with the hope that a more stable SEI on silicon compared to metallic lithium might prevent/suppress several detrimental processes: i) the polysulfide redox-shuttle; ii) the continuous consumption of sulfur via polysulfide reduction and Li 2 S precipitation at the anode; and, iii) the long-term consumption of SEI stabilizing additives like LiNO 3.66 Other additives which are effective for silicon anodes (e.g., vinylene carbonate 67 ) are typically dissolved in carbonate electrolytes. These carbonate electrolytes are shown to be incompatible with polysulfides. 163 Another possible anode alternative might be tin-based electrodes as shown by Scrosati et al. 68On page 2614, left column, third paragraph, the first sentence should be Assuming that the cost breakdown of a battery cell with a metallic lithium anode is similar to that of a battery cell with a graphite anode, and considering that the price of sulfur is negligible compared to NMC111, one would project a cost advantage of about 23% for a Li/Li 2 S (or Li/S) battery cell.