How to Make a Better EV Battery
Updated October 2, 2013
Electric vehicles [EV] of any type, from compact to luxury models, have one thing in common, and it’s their biggest problem. The battery pack in an EV is an engineering headache, a marketing nightmare, and could be the main reason that EVs haven’t gone mainstream yet.
Researchers are discovering that they don’t know as much about lithium-ion [Li-ion] rechargeable battery packs as they thought they did, “so engineers overcompensate by building batteries that are too large,” said Miroslav Krstic, a faculty member of the Department of Mechanical and Aerospace Engineering at the Jacobs School of Engineering.
By experimenting with different materials and different charging controls, a couple of different research teams have been working in opposite directions for the same goal. NEC Corp, in partnership with Nissan, has developed a higher energy-density cell. Researchers at University of California San Diego [UCSD] are developing new algorithms to control Li-ion batteries.
Build it Better
NEC Corp recently announced that it was able to build a new rechargeable Li-ion cell with 30% more energy density. By substituting nickel for part of the manganese in the positive electrode, NEC was able to increase the voltage capacity from 3.8V to 4.5V in the same size package. The polycarbonate-based electrolyte was also upgraded to combat the oxidation caused by the higher voltage. The result of changing to new materials was an increase from 150Wh/kg to over 200Wh/kg.
The new battery design also works better for longer and at higher temperatures. Recharging times would be reduced. and battery lifespan would increase substantially.
Nissan and NEC have been working together on a new longer-range EV battery since 2009, when Nissan’s CEO Carlon Ghosn said, “There is a second generation of battery coming which is less costly than the previous one.” NEC’s latest development, to be revealed at the PriME 2012 electrochemistry conference, running from October 7 to 12, could be the culmination of that research. This development could mean a 30% boost in range for EVs while reducing cost.
Control it Better
On the other hand, perhaps what is needed is better control. Engineers still have a lot to learn about exactly how Li-ion batteries function on a molecular scale. Researchers at UCSD are working at gaining this better understanding. “This research is bringing the promise that, with advanced estimation algorithms that are based on mathematical models, batteries can be charged faster and can run more powerful electric motors,” said Krstic.
UC President’s Postdoctoral Fellow Scott Moura, the co-lead researcher on the project, and Krstic are working on sophisticated algorithms that predict what is going on at the molecular level while cycling, that is, discharging and recharging the battery pack. The current methods of battery health estimation using voltage and current are not good enough to use the battery pack to its full potential.
Krystic and Moura are hoping that their new methods will enable better management of current Li-ion technology, making it possible to work closer to the thresholds of performance. EV batteries could then be built smaller and drive more powerful motors.
Currently, hybrid electric vehicle [HEV] batteries, and probably EV batteries, only run a cycle between 20% and 80% charge, to prevent damage and maximize lifespan. The first and last 20% are just not available for use, so in reality, the battery is 40% larger than it really needs to be.
Toyota just scrapped its second EV, the eQ, before it even launched, citing range and charging issues, but maybe it didn’t have to be so. Now, there’s no wind of this out there, just my hypothesis, but if UCSD’s control algorithms come together with NEC’s battery technology, imagine the outcome!
Maybe the Nissan Leaf could use a 5%-95% cycle run by UCSD’s algorithms, and use 95% of its battery capacity of the improved NEC type. This would calculate to a range 142 miles, nearly double Nissan Leaf’s stock range of 73 miles. All this on the same size battery pack, with recharging time could be cut in half as well.
The thirty-minute talk time of the old brick phone has given way to mobile phones with days of talk time. The electric car doesn’t have to stay dead for long, if the same kind of technological advancements make it into their design.
B. Jerew is an ASE-Certified Master Technician with a keen interest in hybrid/electric technology and alternative fuels. He has written this article in association with GreatHybridCars.com, a rapidly growing destination site for eco-conscious car buyers.
Categories: Gear Grinding