Katie Benner:

But if Apple’s goal is to make an electric car that disrupts the auto industry like the iPhone disrupted smartphones, then the tech that matters the most is the battery. And car battery tech has thwarted many other companies. Building a better battery is a tough chemistry conundrum, not the sort of electronics problem that tech companies are used to solving.
 Just ask the guys at A123 Systems, the startup that got funding from the Department of Energy’s loan-guarantee program before it went bankrupt trying to make batteries for electric cars. Apple was sued for poaching employees from A123 and Tesla to be part of its car team.
 A123 ran into problems trying to make batteries that were effective and affordable, as the MIT Technology Review pointed out when the company went bankrupt. The batteries were so expensive that they made electric cars cost too much to compete with conventional gas-fueled cars (a dynamic that’s exacerbated by low gas prices). Even though the cost to produce a battery has fallen, battery technology hasn’t improved much in terms of longevity or design.