Correspondence

摘要

Nothing would please me more than to see batteries break out of their traditional markets and propel our cars, a goal described in your News Feature 'Charging up the future' (Nature 456,436-440; 2008). In my view, this will not happen, however, because of the weakness of electrochemical power storage. The best lithium-ion battery provides energy at the rate of 100 watt-hours per kilogram. For liquid fuels such as petrol and diesel the energy density is around 12,000 watt-hours per kilogram. Even after dividing the latter figure by four because of Carnot-cycle losses in the conventional car engine, you are still at least 30 times better off with petrol than with the best and most expensive battery.