METRANS UTC

What’s Cool in Transportation – Electric Vehicles (part 2)

Sunday, March 26, 2017 - 6:37am

Shichun Hu

Welcome back to the Electric Vehicles series! During part 1, we talked a bit about the history of electric vehicles and together we found out that it can trace back as early as gasoline powered vehicles.

In part 2, we will look at the state of electric vehicles today. With many different models of electric vehicles on the market or planned for release within the next 5 years, people are surrounded by news of electric vehicles. But is the EV market really taking off?

Table [1] below shows market share of electric cars in different countries from 2005 to 2015. By 2015, the total market share around the world was 0.9% (0.7% in the United States), clearly showing that electric vehicle market is still in its infancy. European countries, in particular those to the north (Norway, Netherlands and Sweden) have much higher percentage of electric cars in their markets than do other countries. As for the U.S., not only is the growth minimal, but there was actually a decrease in 2015 with only 113,588 EVs sold that year compared with 123,049 in the prior year[2].

 

The reasons behind these numbers above are undoubtedly complicated, and beyond the scope of my expertise or column, but my intuition tells me the following. For the European countries, the increasing portion of EVs may be partly due to the pervasive awareness of environment protection and the fact that the range anxiety issue of electric cars is not as significant of a problem in their rather small territories. For the United States, range anxiety does become an issue because of its car-dependent nature as well as the lack of enough charging infrastructure to cover the charging demand. The reasons behind other countries like China (a developing country with vast land but had 1% of EVs in 2015), Japan and Korea (developed country with small land size but had relatively low EV market share) remain to be discussed; if you have any thoughts, please share your ideas with us!

Despite the electric vehicle market status we just discussed, there is no doubt about the significant boost in the future, whether the estimates are modest or positive. The main reason should attribute to the development of battery techniques.

The most common type of battery used for electric vehicles is the lithium-ion battery, which can be categorized according to the anode material. For instance, the anode material in Tesla’s electric cars use is called “lithium cobalt oxides” (LiCoO2). The battery made of this anode material has the advantage of stable structure and high capacity ratio while the disadvantages are low capacity and poor safety level.

2014-08-19%2019.10.42-1280.jpg

Tesla Model S battery pack where thousands of LiCoO2 batteries are assembled together

Source: https://teslamotorsclub.com/tmc/threads/pics-info-inside-the-battery-pac...

There are some other anode materials too. Lithium iron phosphate and lithium ferric manganese phosphate are both good choices in that they possess the properties of high capacity, high safety level, and long lifetime. But they have the issues of low power density and poor performance in low temperatures. Although lithium-ion batteries have all kinds of non-negligible flaws, the researchers and engineers have managed to increase the maximum mileage to 322 kilometers (200 miles) per charge.

In addition to the lithium-ion batteries, we also have fuel cell batteries, recently implemented as a power source in cars (Toyota Mirai[3]). This emission free, fast charge, and long range battery seems to be a better choice in many ways than current mainstream options. Nevertheless, fuel cells have their own problems that need to be addressed. How can dangerous hydrogen be restored in a safer and more efficient way? How long could the complex fuel cell system last? How could we further decrease the manufacturing cost? All these questions stick to the pain point of many companies and customers that restricted the usage of fuel cell batteries. Yet still, knowing that researchers are devoting themselves to addressing technical issues, I personally think this option shall be the future and is promising.

Toyota Mirai powering mechanism

Source: http://www.toyota-global.com/innovation/environmental_technology/fuelcel...

 

Finally, a Nobel winning scientific finding, graphene, has inspired intelligent people all over the world to strenuously seek a way to utilize its superb electrical and thermal conductivity to make batteries like nothing seen before. However, this still remains an idealized concept. No actual breakthroughs have been made to apply graphene or graphene composite materials to the battery cathode. Even the announcement Huawei made in November, 2016, was only to claim that they unveiled a new graphene-enhanced Li-Ion battery that can remain functional at higher temperature and operates twice times longer than previous batteries. But us human beings never stop trying right? Let’s wait and see how it goes.

And that shall end our column for today! My next column will be the final column for electric vehicles. I’m going to keep the specifics a mystery and encourage you to read part 3 of the series for our exciting conclusion to this topic!

 

References

[1] Global EV Outlook 2016, P37.

[2] MotorIntelligence, Inside EVs.

[3] https://ssl.toyota.com/mirai/

 

Shichun Hu

Author Shichun Hu is a student assistant at METRANS Transportation Center specializing in research project administration and coordination of the METRANS Mentor Program. She is a 2nd year graduate student majoring in Industrial and Systems Engineering in the Viterbi School of Engineering, USC. Her interests are using data and operation research methods to improve urban logistics and the supply chain. She is pursuing analytical internships in these fields. Shichun can be reached at shichunh@usc.edu.