Bloomberg News: Lithium-ion batteries are the most expensive part for electric vehicles, at about $1,000 a kilowatt-hour, and most such vehicles will have capacity of about 20 kilowatt-hours, according to General Motors Vice Chairman Robert Lutz. Leasing will let customers avoid the batteries` depreciating value and disposal or resale, according to Nissan, whose new Leaf is an electric car. Nissan, seeking to lead the emerging market for electric autos, said it expects most customers will lease …