Here's some interesting insights on Thomas Edison's 100 year old nickel-iron battery technology, now mostly forgotten. These cells were made commercially between 1903 and c.1975, when 'Exide' closed the East Orange, New Jersey manufactuary that they had aquired 3 years earlier.
http://www.nickel-iron-battery.com/This technology is seeing a possible new lease of life with Stanford U. research, using new forms of engineered carbon nanostructures in the cells to improve the charge/discharge rates. The main use of these cells may be in regenerative-brake storage rather than full traction.
http://www.gizmag.com/scientists-give-new-life-to-thomas-edisons-nickel-iron-battery/23102/The US Gummint recently awarded several research grants of a total of $120m with the aim of developing batteries with 5 times the present power to weight & timescale years ratio as targets specifically aimed at electric-car use and off grid storage.
http://www.electronista.com/articles/12/12/03/research.to.boost.power.five.times.in.five.years/ And here, Edison's boast that his batteries were capable of lasting 100 years even if abused to the limit, are tested and found to be largely true, as some venerable 85 year old cells are bought back to life!
http://www.nickel-iron-battery.com/Edison%20Cell%20Rejuvenation%2085%20yr-old%2013.%20DeMar.pdf
