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New Synthesis Process for Li-Ion Electrode Promises Improved Power and Charge Retention

30 August 2006

Researchers at the University of St. Andrews in Scotland have devised a new approach to synthesize an electrode material for lithium-ion batteries that provides superior power and charge retention. They describe their results in the latest issue of Advanced Materials.

Lithium-ion battery electrodes use intercalation materials. These materials are composed of a solid network of lithium atoms together with other metals, such as cobalt, nickel, or manganese meshed together with oxygen atoms.

When you charge a lithium-ion battery, the charging current pulls the positive lithium ions out of this network. Then, when you use the battery, it discharges as these lithium ions migrate back into the electrode, pulling electrons as they go, and so generating a current.

The challenge is to make new electrode materials that deliver high power (fast discharge) and high energy storage. To address these issues, Kuthanapillil Shaju and Peter Bruce developed a new way of synthesizing a particular lithium intercalation compound (Li(Co1/3Ni1/3Mn1/3)O2). As a bonus, they hoped to be able to simplify the complicated manufacturing process.

The St Andrews team approach involves simply mixing the necessary precursor compounds—organic salts of the individual metals—with a solvent in a single step. This is in contrast to the conventional multi-step process used for making the compound. Using this technique, they were able to make highly uniform lithium oxide intercalation materials in which nickel, cobalt, and manganese ions are embedded at regular intervals in the solid, which also contains pores for the electrolyte.

The highly porous nature of the new material is crucial to its electrical properties. The pores allow the electrolyte to make intimate contact with the electrode surface resulting in high rates of discharge and high energy storage.

The St Andrews team has tested their new lithium electrode material by incorporating it into a prototype battery and found that it gives the battery far superior power and charge retention.

Increasing the rate by 1,000%, so that the battery can be discharged in just six minutes, reduces the discharge capacity by only 12%. The test results suggest that this approach to rechargeable batteries could be used to make even higher power batteries for vehicles and power tools.

There’s an added bonus in that replacing a proportion of the cobalt used in the traditional lithium-cobalt-oxide electrodes with manganese improves safety by reducing the risk of overheating.

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it's possible that this is just the step we need to bring EVs to fruitation.

It sounds like a very expensive process actually, which means we'll see it first in cel phone and portable music player batteries, followed by laptops, and after costs continue to decline would it lead to larger format applications like PHEV's.

Sounds like we haven't seen the end of development in battery technology.

With six minutes charge time, 150 miles range would actually be sufficient for most people, provided high power outlets were easy to find, e.g. at existing gas stations (uhmm - high currents and gasoline fumes... maybe not the best combination...).

I'd have no problem with a 6-7 minute stop for every 2-3 hours of driving. Don't forget, you'd be much less likely to leave home with "half a tank" of electricity than now, since you plug it in at night.

Keep up the good work battery-scientists-guys! :-)

Looking for a little clarification. This article talks about vastly improved discharge rates (at a 12% power penalty). Is there any change to the charge rate? There is mention of charge retention but no specifics. By charge retention are you refering to capacity or the ability to hold the charge over time? Cost reduction sounds great, wonder how much.

Sid, I don't know anything about battery manufacturing, but why is this more expensive than existing Li-Ion manufacturing methods?

Are there hidden costs/complexities in preparing the organic salts?

As to possible uses, existing handheld devices seem to me to be more limited by battery capacity rather than power. Other than some benefit in safety (see recent Sony debacle - hope they didn't use these batteries in the Tesla Roadster!) it doesn't seem as that relevant for a cellphone-type profile. Do these devices, at their occasional "high drain" (i.e. radio on) mode, move too far off the efficient part of the Li-Ion discharge envelope?

Occasional-high-power uses, on the other hand, like, say, a car...

Battery geeks on GCC: For a rechargeable battery chemistry, is it safe to assume that high power implies fast charge and vice versa?

For cost, I was basing it on both the fact that new technology tends to be more expensive at first than the old stuff, plus the line of the article that states they hope to be able to simplify the process. Complex = expensive, but let's hope they can compete well on cost.

Consumer don't need fast discharge rates, but they can be greatly assisted by fast charge rates. Just take a look at contemporary NiMH chargers and you'll see usually the #1 largest marketing words on the product speak to how fast it charges. Same for many laptops and digital cameras that state something like "1 hour of usage from just a 10 minute charge!!!"

A cel phone that can get 30 minutes of talk time from 2 minutes in a power socket would be a highly desireable option. Likewise, many laptop batteries that provide extended runtime, such as the ThinkPads that have the 100 watt/hour batteries providing up to 10 hours of runtime (more like 2-3 hours with intense use of the CPU and optical drive) would be highly desireable if a traveler on a short layover between flights could just find a wall socket somewhere to plug in for 10 minutes and fully charge up his laptop.

1 hour from a 10 minute charge has to do with a number of factors:

1. Clever circuit design for greater efficiency.
2. Clever wording as 1 hour of use may have an industry standard with a duty cycle where actual use of energy intense processes is very limited (e.g. in radios 5% rx 5% tx and 90% standby is considered normal use).
3. May only be repeatable under laboratory conditions and not many consumers will get out a stopwatch and test such claims unless they are very far off the mark.

...seldom is it due to the chemistry of the batteries (charging/conditioning techniques advance at about the same rate as chemistry advances...and software advances for that matter).

with this kind of quick discharge characteristics this chemistry seems more suitable for HEVs than pure EVs (or maybe even PHEVs) since it would allow for smaller batteries that provide enough power for initial accelleration.

A lot of hype and very few hard numbers. They brag about power density which is not very important and don't mention energy density which is the most important spec along with cost for EV's and hybrids.

--Engineer and Freedom Fighter

Sadly, the "breakthrough" battery announcements all read pretty much the same. Valence and A123 systems have fast charging Lithium Ion batteries, with an energy density around 100 Wh/Kg and a cost around $1000 per KWH. A true breakthrough would be a fast charging Li-Ion battery with a power density of around 200 Wh/Kg, and a cost of $300 per KWH. Perhaps a historical graph would be nice, showing the goal, and showing how close to the goal each of these "breakthrough" innovations actually comes in relation to what is already out there.

It's interesting to imagine a world where cars are EVs. The fueling (charging) infrastructure would be pretty different from today. Most charging would be at home or at work. Maybe shopping centers would provide free charging in order to encourage people to shop there. (They could trickle charge to reduce their expenses.)

Gas stations would be replaced by charging stations, but they would be much less common. They would be used only for long distance travel. They would be located on the big interstate highways, and perhaps at the entrances and exits to towns and cities, like truck stops today. The neighborhood gas station would disappear, it would not get enough business recharging batteries to be economical.

Hal, the "neighborhood" gas station makes more money inside the store then they do from the gas pumps.

Van, what's your source on the "energy density around 100 Wh/Kg and a cost around $1000 per KWH."??

I've been trying to find costs for A123ystems batteries to no avail. There are cost figures for Dewalt batteries, but no specs that I've been able to find. They do seem cheaper than that...

The charging statioins are already there. Those chain link enclosures the electric utilities have spaced around everywhere can handle the quick charge needs
ov several vehicles at once. Which probably scares the hell out of oilman Bush and Halliburton chaney. We wont be connected to a oil company tank for gasoline or hydrogen.

Merrill Davis,
We would be at the mercy of our power source, transported over our overburdened power grid. It would also be powered largely via fossil energy, namely coal. This means more GHGs and more demand for coal from mines, possibly causing more deaths and scarring landscapes (they sometimes remove whole mountaintops, then dump the debris in valleys and streams). There may be hope with combined cycle gas+steam turbine plants that may increase effeciency and output by 50% w/out increasing the amount of fuel burned.
_
___NIMBY, however, will slow building new high tension power lines to a crawl. That may leave the solar potential locked in the Southwest, or maybe including states on the Mississippi River and west of. Stringing HVDC or 3phase HVAC is easier in and through less populated areas. Buying farmland, and putting them up through deserts would be less politically challenging, to say the least.

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