Is Li-ion the Solution for the Electric Vehicle?

Battery manufacturers are tooling up for the electric vehicle, but what would happen if it failed? Could there be a déjà vu of the fuel cell in the 1990s, or the bio fuels in the last decade? The US Department of Energy (DOE) has admitted that some critical parameters of Li-ion are not met. Newer NiMH batteries, which are cheaper and safer than Li-ion, are also suitable for the electric powertrain but these mature systems are often excluded from government grants for research.
 
There are no ideal contenders for the electric powertrain, and lithium-ion remains a good choice. Out of the five candidates illustrated in Figure 1, Li-nickel-manganese-cobalt (NMC), Li-phosphate and Li-manganese stand out as being superior. The popular Li-cobalt (not listed) used in consumer products was believed to be not robust enough; nevertheless, this high energy dense “computer battery” powers the Tesla Roadster and Smart Fortwo ED.
 
Figure 1: Batteries for Electric Cars. Challenges, opportunities and outlook for 2020
The compromises are in safety, energy density, cost and temperature performance. 
Note: The further the shapes extend outwards on the axis, the better the battery will be.
With special permission from the Boston Consulting Group (BCG), ©2010

The above table compares batteries in terms of safety; specific energy, also known as energy density or capacity; specific power, or the ability to deliver high current on demand; performance, the ability to function at hot and cold temperatures; life span, which includes the number of cycles delivered as well as calendar life; and finally cost. The figure does not mention charge times. All batteries offered for EV powertrains can be charged reasonably fast if a suitable electrical power outlet is available. A charge time of a few hours is acceptable for most users, and super-fast charging is the exception. Nor does the table reveal self-discharge, another battery characteristic that needs scrutiny. In general, Li-ion batteries have low self-discharge, and this parameter can mostly be ignored when the battery is new. However, aging when exposed to heat pockets can increase the self-discharge of the affected cells and cause management problems. Among the EV battery candidates, Li-phosphate exhibits a higher self-discharge than the other systems.

None of the five battery candidates in Figure 1 show a significant advantage over others, and the size of the spider fields are similar in volume, although different in shape. Focusing on one strong attribute inevitably discounts another. NCA, for example, has a high capacity but presents a safety challenge, whereas Li-phosphate is a safer system but has lower capacity. In the absence of a clear winner, car manufacturers include peripherals to compensate for the deficiencies. Battery manufacturers in turn assist by custom-designing the cell to strengthen the important characteristics needed for the application. Here is a brief summary of the most important characteristics of a battery for the electric powertrain.
 
Safety is one of the most important aspects when choosing a battery for the EV. A single incident blown out of proportion by the media could turn the public against such a vehicle. Similar concerns occurred 100 years ago when steam engines exploded and gasoline tanks caught fire. The main concern is a thermal runaway of the battery. Carefully designed safety circuits with robust enclosures should virtually eliminate this, but the possibility of a serious accident exists. A battery must also be safe when exposed to misuse and advancing age.
 
Life Span reflects cycle count and longevity. Most EV batteries are guaranteed for 8–10 years or 160,000 km (100,000 miles). Capacity loss through aging is a challenge, especially in hot climates. Auto manufacturers lack information as to how batteries age under different user conditions and climates. To compensate for capacity loss, EV manufacturers increase the size of the batteries to allow for some degradation within the guaranteed service life.
 
Performance reflects the condition of the battery when driving the EV in blistering summer heat and freezing temperatures. Unlike an IC engine that works over a large temperature range, batteries are sensitive to cold and heat and require some climate control. In vehicles powered solely by a battery, the energy to moderate the battery temperature, as well as heat and cool the cabin, comes from the battery.
 
Specific energy demonstrates how much energy a battery can hold in weight, which reflects the driving range. It is sobering to realize that in terms of output per weight, a battery generates only one percent the energy of fossil fuel. One liter of gasoline (1kg) produces roughly 12kW of energy, whereas a 1kg battery delivers about 120 watts. We must keep in mind that the electric motor is better than 90 percent efficient while the IC engine comes in at only about 30 percent. In spite of this difference, the energy storage capability of a battery will need to double and quadruple before it can compete head-to-head with the IC engine.
 
Specific power demonstrates acceleration, and most EV batteries respond well. An electric motor with the same horsepower has a better torque ratio than an IC engine.
 
Cost presents a major drawback. There is no assurance that the battery’s target price of $250–400 per kWh, which BCG predicts, can be met. The mandated protection circuits for safety, battery managements for status, climate control for longevity and the 8–10-year warranty add to this challenge. The price of the battery alone amounts to the value of a vehicle with IC engine, essentially doubling the price of the EV.
 
To reduce pollution and save on fossil fuel, governments are promoting the electric car. This done in good faith, but looking at Figure 2 we may come to realize that this may not be possible with present technology. Many readers will agree that the success of the car was made possible with very low fuel prices in terms of net calorific value. The notion of driving a large vehicle for long distances may not be transferable to battery propulsion, even with government subsidies. The battery is a weak contender against diesel and gasoline, and this is visible on the chart. Li-ion, the battery choice for the electric vehicle, is hardly visible on the horizon, and the 90 percent efficiency of the electric motor does not make up for the low net calorific value.
 
Figure 2: Net calorific values of fuels with conversion efficiencies
NCV of diesel and gasoline surpass hydrogen and Li-ion. The conversion efficiency refers to unit output and does not include drag factors.

*    CNG (compressed natural gas) is at 250 bar (3,625psi)
**  Hydrogen is at 350 bar (5,000psi)
 
Hydrogen is also being dwarfed by diesel and gasoline. The slightly better efficiency of the PEM fuel cell in energy conversion compared to the IC engine has only a marginal benefit. In addition, hydrogen cannot be pumped from the earth as oil and needs energy to generate. In this respect, hydrogen is similar to a battery; it is a storage media to make energy portable.
 
Let’s respect liquid fossil fuel for as long as we have it because alternative resources will be more expensive. Daimler’s CEO, Dieter Zetsche, knows this and stressed at a meeting in Stuttgart that major research and developments are needed now because, “in the long run there’s no alternative to the electric vehicle.” EV makers also know that the investment is high and the return low.
 


*** Please Read Regarding Comments ***

Comments are intended for "commenting," an open discussion amongst site visitors. Battery University monitors the comments and understands the importance of expressing perspectives and opinions in a shared forum. However, all communication must be done with the use of appropriate language and the avoidance of spam and discrimination.

If you have a question, require further information, have a suggestion or would like to report an error, use the "contact us" form or email us at: answers@cadex.com. While we make all efforts to answer your questions accurately, we cannot guarantee results. Neither can we take responsibility for any damages or injuries that may result as a consequence of the information provided. Please accept our advice as a free public support rather than an engineering or professional service.

Comments

On January 19, 2011 at 12:22pm
Jaime wrote:

Interesting conclusions.

(Please, check the meaning that you gave to “specific energy”)

On January 19, 2011 at 4:39pm
BWMichael wrote:

I think we should stick to petrol cars. Much easier

On August 27, 2011 at 4:28am
Ian wrote:

“One liter of gasoline (1kg) produces roughly 12kW of energy…”

A kilowatt is power. A kilowatt-hour or a joule is energy, which is what you should be talking about.

On September 5, 2011 at 4:18pm
rex wrote:

i agree with bwmicheal i will just stick to petrol cars so i will be having lesser problems in the future. you will gain power on your car if you will be making some modification like installing body kits or hood struts to generate more horse power on your car.

On September 5, 2011 at 4:26pm
Ian wrote:

rex, if installing body kits or hood struts generates more horse power on your car then adding racing stripes along the sides must blow the horsepower off the top of the dynamometer.

On September 5, 2011 at 5:15pm
Ian wrote:

“Note: The further the shapes extend outwards on the axis, the better the battery will be.”

If considering just cost, at present lithium titanate is the least attractive because of its high cost. If cost was not an issue it would be quite good.

On November 2, 2011 at 8:14pm
Ginger wrote:

Great article. very informative.

On January 24, 2012 at 1:26am
Rick Cantu wrote:

Keep me informed.

On May 8, 2012 at 11:51pm
jean genibrel wrote:

Does anyone know of a manufacturer who could supply cells the be connected to produce 12 volts nominal. Also I would need cases to put them into and connectors etc. Chargers also

On May 8, 2012 at 11:53pm
jean genibrel wrote:

Does any one know where I could buy cells to make large batteries of 12 volts nominal? I will also need cases and connectors. How a bout chargers?

On May 27, 2012 at 1:51pm
JPWhite wrote:

@BMWMichael

So you want to stick to gasoline eh?

Did you gloss over the bit Daimler said.
“in the long run there’s no alternative to the electric vehicle.”

Sticking our heads in the sand is NOT going to avoid the inevitable.

On October 10, 2012 at 2:02am
ddubrule wrote:

Is there information somewhere about Lithium-Ion batteries for scotters?  I am a senior living in Victoria, BC, and I figure I could get around with a scooter or something else a little smaller than the Smart car.  However, I would want to have a relatively small battery and at least a 30 mile driving range.  Any suggestions?

On October 10, 2012 at 4:22am
JP White wrote:

@ddubrule

Nogas scooters are manufactured in Nashville close to where I live. They have two models, 35 mile and 50 ranges. Not sure if they sell to Canada or not.

Here’s their webpage
http://nogasamerica.com/

On March 17, 2015 at 10:19pm
Curt Litza wrote:

While electrical cars seem to be the wave of the future mostly by benefiting the environment; I don’t think these types of cars with lithium style batteries can be produced on the level petrol cars are.  Lithium is a very rare and expensive element here on Earth.  We need to develop a battery that can perform like the lithium ones but has a main element that is in more abundance and is cheaper to obtain and manufacture for civilian use.

On March 23, 2015 at 6:27pm
Matthew Gooch wrote:

Curt, you are absolutely right and I think that we have that capacity to find new and common elements, look at graphene for example it is common. The problems with a lot of these newer energy systems that use things like “saltwater” and “graphene” is that the cost of production is too much to mass produce until we finder cheaper ways of production, also government sanctions and regulations hinder technologies that are cheap and abundant like the hydride fuel cell or the water fuel cell.

On June 12, 2015 at 11:29am
Roja wrote:

which is the best battery to use in electric car??

On March 31, 2016 at 8:35pm
Aaron Fuksa wrote:

Just have to give it time for batteries to evolve for the next generation to use.  Batteries are getting more energy dense every year!  I have a electric bicycle that will go more than (300 miles!!!).  I use lion panasonic batteries.  Guineas world record setting attempt this year.  Let’s stop polluting are earths air with noise and smog.  Make the minority EV’s a majority for future change.  Stop smoking me out, or I’ll out I’ll honk & out accelerate your heep.

On April 8, 2016 at 12:17pm
justin harder wrote:

hello! yeah i somewhat concord with the petrol use but skiptically since it has caused some great world woe of global warming! i have a great idea which really can save the world when it comes to petroleum use, a combination of solar panels @the car bonets and roofs , wind dynames having propellers installed infront of cars and batteries of lithium-ion can power a car for eternity without breaking for recharge at power stations. the plastic solar panels are light in mass and dynames of 12V output are light too and this would do the real magic, i felt like my ideas are right and i feel like trying them out but it hurts that i’m just a poor someone till i finish up my father’s course of pharmacy then i will start my real engineering life to change the cosmos, thanks and great regs from East Africa Uganda

On May 14, 2016 at 3:53pm
John Metadata wrote:

This article should be updated and mistakes (12 kW of energy?) fixed.

On May 5, 2017 at 12:51pm
Sigma Institute of Energy & Environment, New Delhi wrote:

India is coming in a big way in Electric Vehicle. I want to introduce a course in my institute on batteries used in cars and their chargers. Please suggest. Harish Chawla +91119810034342

On June 24, 2017 at 6:06am
UNknown1 wrote:

I was actually thinking a liquid cooled battery compartment and photo voltaic might be the idea candidate for this. as gamers who overclock for long periods tend to use the same method. however we seem to be at an impasse here as no one seems to have any clue as to where to/how to accommodate these features.