Three Energy Storage Battery Technologies for Vehicles

1. Lithium ion batteries

At present, most electric cars use lithium iron phosphate batteries, but there are several difficulties in popularizing electric cars using lithium batteries:

 First, the price. Batteries account for more than half of the cost of electric cars, and the latest Tesla cars cost more than 700,000 RMB, out of the reach of ordinary people.

 Second, energy density. The theoretical specific capacity of lithium iron phosphate battery is 170Wh /kg, and that of lithium cobalt acid battery is 200Wh /kg. So most of the load on a lithium-ion car is the weight of the battery.

 Third, Security. This still needs to be tested by time, in a long-term perspective.

 Fourth, charging time. In the quick charge mode, the battery can be 80% full in a few minutes, but the battery will endure relatively severe damage, and there is some danger. Slow charging takes several hours to a dozen hours. Manufacturers generally recommend the slow charging mode.

2. Super-capacitors

There is no solid evidence of the report that super-capacitors would replace batteries. Although the energy density of the super-capacitors will be greatly improved after the introduction of graphene, it is still much lower than that of lithium ion battery, being only 74Wh/kg. But super-capacitors have the advantages of being quick to charge (in a few seconds) and safe, and can be used for auxiliary regulation of the peak-load and as the storage energy for the brake of electric vehicles.

3. Hydrogen-powered vehicle

The technologies of hydrogen-powered vehicles have made great progress in recent years, with advantages of short charging time and strong power. The problems we have to solve for hydrogen cars right now are：   

1) The production cost of hydrogen  

 2) Safe and high-strength hydrogen storage tanks  

 3) security  

 4) The price of gas-filled equipment 

Among them, the issue of security is particularly important. There is also controversy over whether hydrogen is produced in an environmentally-friendly way.