New algorithms could allow lithium-ion batteries to charge twice as fast


October 5, 2012

Miroslav Krstic (left) and UC President's Postdoctoral Fellow Scott Moura have developed estimation and control algorithms that improve the efficiency of lithium-ion batteries (Photo: Jacobs School of Engineering)

Miroslav Krstic (left) and UC President's Postdoctoral Fellow Scott Moura have developed estimation and control algorithms that improve the efficiency of lithium-ion batteries (Photo: Jacobs School of Engineering)

The single biggest factor hindering the convenience, and therefore the adoption, of electric vehicles is the batteries used to power them. While filling up an ICE vehicle takes just a few minutes at the pump, electric vehicle recharge times are measured in hours. Engineers at the University of California, San Diego, have developed new algorithms that improve the efficiency of existing lithium-ion batteries and could allow them to be charged twice as fast than is currently possible.

Toyota is so concerned about the limitations of EVs it recently announced it would severely limit the availability of its Scion iQ EV microcar in favor of hybrid vehicles. While most research efforts to overcome the limitations of lithium-ion batteries focus on using new materials, such as graphene, carbon nanotubes or even sugar, the sophisticated estimation algorithms developed by Professor Miroslav Krstic and UC President's Postdoctoral Fellow Scott Moura at the Jacobs School of Engineering at UCSD promise to make existing lithium-ion battery technology more effective.

Lithium-ion batteries comprise three layers – an anode, a cathode, and a separator layer – all of which are rolled together to form a cylinder. When fully charged, the lithium ions are stored at the anode before moving through the separator layer to the cathode when powering the device to which the battery is connected. Knowing where the ions are in the anode provides an indication of whether the battery is functioning properly, but since the ions are usually lodged deep inside irregularly-shaped particles within the anode, this is very hard to measure.

As a result, manufacturers currently monitor a battery’s behavior and health by measuring the voltage and current. Krstic says this is a crude measure and results in batteries that are oversized, weigh and cost more, and take a long tome to charge.

The estimation and control algorithms developed by Krstic and Moura allow them to estimate where the particles are so the anode can be filled to capacity safely and efficiently. The algorithms can also estimate how the health of the battery changes over time. The researchers claim their approach has the potential to reduce the production costs of lithium-ion batteries by 25 percent, while also allowing them to run more powerful electric motors and slashing charge times in half.

The researchers have received a US$460,000 share of a $9.6 million grant from the Department of Energy’s ARPA-E research agency. They are sharing the grant with automotive product supplier Bosch and battery manufacturer Cobasys, who will supply testbeds on which Krstic and Moura will refine and test their algorithms using actual batteries. The first step will see them estimating the charge distribution within the battery before estimating its state of health. The final step will be to find the optimal charge and discharge rates of the batteries.

Source: UCSD Jacobs School of Engineering

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

Actually, the Tesla batteries would take half charge in a half hour, but then slow down as they fill (like any battery). But doubling speed is still a big deal.

Brian Hall

WOW, that is awesome! This is big news for everything that uses batteries...which is a whole lot of stuff these days.

Also its big news for electric cars. Last week Tesla unveiled its SuperCharger network, which can fully charge your Model S in 1 hour, if this tech could make that a half hour, that would be a big step in the right direction.

Derek Howe

Altairnano's nLTO already enables continuous 6C cont& 10C peak (6-10 minute) charges. Cycle life is 16K cycles @ 100% full DoD to 80% capacity; and upward of millions at low partial DoD. Safety attributes are best in class, offering extremely wide operating parameters for customers. Third party testing exists on these attributes (which can be provided to you) or you can test yourself. Let me know if you would like any further information and/or reference Proterra’s website for an example of how this technology has been applied within a rapid-charge EV transit bus application currently operating in multiple USA cities.

Cynthia Kolb
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