Autumn for the Leaf? Part One
Posted by Jeff Id on June 12, 2011
If we are to achieve a truly zero carbon economy using discontinuous sources like wind, then energy storage is key. I follow the news on this topic closely and storage advancements are coming almost daily but how far and fast will the technology progress? – Jeff Id/Elmer Fudd——–
guest post by Robert Allaband
One of the sites that I peruse off and on through out the day is Instapundit (http://pajamasmedia.com/instapundit/ ) because the author, Professor Glenn Reynolds, links to some very interesting stories. One that is of interest he had titled: MIT students develop liguid fuel for electric cars. He provided a link to another site called Gas2.org and an article about a paper released in the journal Advanced Energy Materials.
Semi-Solid Lithium Rechargeable Flow Battery
Mihai Duduta, Bryan Ho, Vanessa C. Wood, Pimpa Limthongkul,
Victor E. Brunini, W. Craig Carter, Yet-Ming Chiang*
Here is the link to the MIT press release:
Now flow batteries are nothing new you can find them in your UPS backup for your computer and you can read up on them here:
The paper goes into detail how the Semi Solid Flow Cell (SSFC), in the prototype they have, overcomes the limitations of a typical flow battery. Now the authors of the paper, specifically Dr. Ching, are not new comers to the field of making batteries for electric cars. Dr. Ching was responsible for some of the breakthroughs on Lithium Ion batteries and a co-founder of A123 Systems:
A123 Systems (NASDAQ: AONE) develops and manufactures advanced lithium-ion (lithium iron phosphate) batteries and battery systems for the transportation, electric grid services and commercial markets. The company has 1,700 employees and is headquartered in Waltham, Massachusetts.
Founded in 2001 by Dr. Yet-Ming Chiang, Dr. Bart Riley and Ric Fulop, A123 Systems’ proprietary nanoscale electrode technology is built on Massachusetts Institute of Technology research. In 2009, the company was included on the Guardian‘s “Global Cleantech 100” list. </blockquote>
Now the thrust of this article isn’t in the nitty gritty of what makes (or doesn’t) a SSFC work. The thrust will be the two problems that the MIT team says the SSFC or technology similar to it will overcome that in my opinion prevent wide acceptance of electric vehicles. The first problem is just about universally recognized and gets almost all the attention: Energy Storage.
The problem in batteries is a compromise between size and capacity. Reduce the size of your battery and you also reduced the capacity of how much energy is stored and the reverse is generally true. So in a passenger vehicle you are restricted in how much maximum space a battery can take up and still be a worthwhile vehicle, competing against the need for this vehicle to have a large enough battery to give enough performance and operating time to make it a worthwhile vehicle. This has been known since the time of Edison and Ford when they tried to make a battery powered vehicle. They coudn’t overcome this problem and Ford went with the Internal Combustion Engine (ICE).
However times change and technology improves or least that is what you would think, however most of the basics of what we use in battery technology is little changed from the 1800’s. An example of this is the Nickel Cadium (NiCd) battery. Remember those?
Rechargeable batteries for your handheld electronics and power tools were first developed to use the Nickel Cadium rechargable battery. Now guess when that battery was invented? 1899. We have just miniturized it over the years with slight efficiency increases and this process was started in 1955.
The next step after that was the nickel hydrogen battery of the 1970’s for satellites which led to the next step in 1989 of the nickel metal hydride (NiMH) battery that replaced NiCd’s in most handheld electronics and power tools.
That is where we stood until modern science thought up lithium and lithium ion batteries right? Nope.
Lithium batteries were invented in 1912 and it was in 1980 that we started playing around with the Lithium Ion battery technology and they didn’t go on sale until 1991. In 1996 we came up with Lithium Ion polymer batteries.
So here we are in 2011 trying to convert from internal combustion engines (ICE) to battery driven Electric Vehicles (EV’s) with technology that is 15 years old and most of the major advances in batteries happened in the 1800’s and into the early 1900’s (1859 the lead acid battery was invented, 1899 the NiCd, 1912 the Lithium battery). Basically we have already picked the low hanging fruit and the recent advances in battery technology are just incremental in nature.One of the reasons for this is brought up in the paper:
However, most batteries have designs that have not departed substantially from Volta’s galvanic cell of 1800, and which accept an inherently poor utilization of the active materials. Even the highest energy density lithium ion cells currently available, e.g., 2.8–2.9 Ah 18650 cells having > 600 Wh L − 1, have less than 50 vol% active material. The reduced energy density, along with higher cost, result because the high-energy-storage compounds are diluted by inactive and costly components necessary to extract power (e.g., currentcollector foils, tabs, separator ﬁlm, liquid electrolyte, electrode binders and conductive additives, and external packaging). Further dilution of energy density, by about a factor of two, occurs between the cell and system level. Electrode designs that minimize inactive material, bio- and self-assembly, and 3D architectures are new approaches that promise improved design efﬁciency but have yet to be fully realized.[5–9]<
To put it more simply, with the battery tech we use today, the battery is trying to do two jobs in one package: Storage and Delivery and neither one to its best advantage. The space and materials used to get the power in and out of a rechargable battery takes away from how much storage capacity that battery has. It doesn’t matter if the battery is a Lithium Ion from 2011 or a Lead Acid from 1860, that limitation is built in since both use the same basic principals. To get a large increase in battery performance we need to separate the jobs of storage and delivery.
Redox flow batteries are designed to overcome those type of limitations by separating the storage and delivery components of the system, but have a limitation of their own: parasitic mechanical losses. Basically the energy required to pump the liguid around detracts from the battery systems efficiency. Because the liquid medium in a redox flow battery has a low density energy storage it limits the uses of them. That is where the SSFC style technology comes in, they use the best of both systems, the decoupling of storage and delivery of a flow battery with the high desity aspects of lithium.
What does this mean in an EV if it all pans out? You are able to significantly increase the range/performance of the EV with out a significant increase of space used or in weight. It also means instead of having to replace the entire battery system if something goes “bad” you can just replace a smaller part at much lower cost thus increasing the worth of the EV years down the road. On the practicle side it removes one big sticking point for a lot of people when it comes to EV’s: No need to plug in and wait hours to be ready to go.
We show that in addition to energy density advantages, the SSFCs can operate at low ﬂow rates with very low mechanical energy dissipation. The design ﬂexibility inherent in the SSFC approach may enable new use-models for electrical storage, such as rapid refueling of vehicles by fuel or fuel tank exchange, tuning of suspensions as needed for power, energy, and operating temperature, and extension of service life by renewing suspension chemistry or incorporating serviceable system components.
Unlike the Lithium Ion battery, the SSFC’s medium of energy storage is contained in a separate tank from the solid and fixed anodes and cathodes. This in turn means you are dealing basically with a liguid material that can be pumped in and out of a fixed tank or replaced via a modular tank system (Fuel Cell system). If this sounds like a familiar system of energy transfer it should, it’s the way we fuel ICE vehicles today. The only difference is that the energy medium is not burned up as you get with Gas or Diesel, instead you have to pump that out first before you refill. However there is already systems used for vehicles on the market that can be converted to that type of use. They are used by mechanics that maintain large fleets of vehicles to remove the used oil from them. Basically you just remove the drain plug from the pan and replace it with an adapter that ends in a quick connect fitting. That fitting is used by a vacuum system to pull the used oil out of the drain pan and into a collection tank for recycling. See the link provided on how the system works and it has been around since 1999.
Just convert that for use for the SSFC medium. After that pump in the new liguid and away you go. A system like that could have you on the road in as little as 2 to 5 minutes.
This system also solves the second and much less talked about problem with EV’s: Infrastructure.
This will be covered in the second part.