Many people think electric cars are the wave of the future, and they may be, but there will have to be a vast improvement in batteries before that can happen. The standard batteries of today, which electric cars, as well as cell phones, iPods, and notebook
computers, all run on are called lithium-ion batteries.
There are basically two ways of storing electrical energy in batteries. The first is a standard battery, in which the whole material of
the electrodes stores energy. This method allows lots of energy to be stored, but these types of batteries are stingy and don't readily
release their energy. Plus they take a long time to recharge.
The second type of battery is called a "super-capacitor," and it stores energy only on the surface of the electrode. Because of this,
super-capacitors charge and discharge very quickly, but they can't hold much energy. The big prize in battery research is finding a
material that can both store a lot of energy, like a lithium-ion battery, and release it quickly, like a super-capacitor
What is the main idea of this passage?
A. Standard batteries are slow to recharge.
О В. There are two basic battery types.
C. There is a big prize for a good battery.
D. Super-capacitors are better batteries.