Most common use for electric cars today are lithium Ion batteries with different chemical composition.
Below is a very helpful chart that explain the performance parameter of Li-ion batteries. So higher the bar goes so better the values are. Let me explain the 6 key performance indicators.
This is an extract from Boston Consulting Group that you can download here.
1. Specific energy
Is actually the energy density of a battery. How much power (watt) storage per weight of the battery can be stored.
2. Specific Power
Specific Power is the amount of power (watt) that can be delivered per weight.
How safe is a batteries in operation is the safety shown by the safety indicator.
How much power can a batterie deliver in an amount of time.
5. Life Span
How many times can you recharge a batterie before the storage or performance degrade.
Actually the longest life span of batteries has currently the Tesla Roadster.