Shell Oil President Questions Need for New Refineries
CalCars Working With Electro Energy on New NiMH Battery Pack for Plug-in Prius

Lead-Acid Batteries for Hybrid and Electric Applications

Although most of the market’s development focus is on advanced battery technologies such as NiMH or Lithium-ion, some companies are still working to improve on the venerable lead-acid platform. Accordingly, there are hybrid and electric vehicle manufacturers who are opting to use or at least to test some of these lead-acid variants in their vehicle applications.

Two of the more recent examples are e-max’s use of a lead-acid battery with a low-sodium silicate electrolyte (“silicon power battery”) in its electric scooter, and the recently announced testing of Power Technology’s advanced glass matt lead-acid battery prototype by an unnamed “major hybrid automobile manufacturer.”

Invented in 1859 by French physicist Gaston Planté, lead-acid batteries are more than 145 years old. The lead-acid battery has evolved significantly into different types over the years, although the basic electrochemistry of them all is the same.

In a lead-acid battery, the negative electrode is lead (Pb), the positive electrode is lead dioxide (PbO2) and the electrolyte is a dilute solution of sulfuric acid (H2SO4).

As the battery discharges, the active materials in the electrodes (lead dioxide in the positive electrode and lead in the negative electrode) react with sulfuric acid in the electrolyte to form lead sulfate and water. On recharge, the lead sulfate on both electrodes converts back to lead dioxide (positive) and sponge lead (negative), and the sulfate ions (SO42- ) are driven back into the electrolyte solution to form sulfuric acid.

Lead-acid batteries have one of the worst energy-to-weight ratios (lead is heavy), although the energy-to-volume ratio is good. They are inexpensive and can supply the high surge currents needed in starter motors—one of their most pervasive applications.

There are three basic types of lead-acid batteries on the market today: flooded (or wet), gel cell and absorbed glass mat (AGM).

Flooded (or wet) lead-acid batteries have their electrodes immersed in liquid electrolyte. Gases created during charging are vented to the atmosphere and distilled water must be added occasionally to bring the electrolyte back to its required level. The most familiar example of this type is the conventional 12V automobile battery.

Gel cell batteries use fumed silica in the electrolyte, causing it to harden into a gel. On subsequent charges some water is lost, drying the gel until a network of cracks and fissures develops between the positive and negative electrodes, decreasing performance.

Absorbed glass mat (AGM) batteries immobilize the electrolyte with a highly porous and absorbent microfiber glass mat.

The “silicon power battery” used in the e-Max electric scooter is a variant of the lead-acid gel cell. Developed and manufactured by Guangdong Jiangmen Yuyang Special Batteries in China, the silcon power battery uses a low-sodium silicate compound and a new method for forming the gel that, according to the company, decreases hazardous emissions during manufacturing, reduces cracking in the battery gel under operation, reduces the self-discharge rate and increases specific energy and cycle life.

E-max had been using Nickel Zinc batteries in other scooter models.

Battery typeEnergy density
(Wh/kg)
Cycle lifeCharge time
(hrs)
Efficiency
(%)
Cost
($/Wh)
Source: e-max
Lead-acid 30–40 100-300 6–8 65 0.12–0.36
Nickel Zinc 60 >500 5 65 0.60–0.73
NiMH 80 >500 14–16 65 1.20–3.60
“Silicon Power Battery” 45-52 >500 2–3 85 0.36–0.42

The advanced glass mat battery developed by Power Technology that is undergoing testing by the unnamed hybrid manufacturer replaces the lead plates or grids of conventional lead-acid batteries with lead-tin alloys deposited on lightweight, open pore substrates such as carbon or aluminum to enhance the cyclability of the resulting high-surface area electrode for use as an anode and/or cathode in lead-acid batteries.

Power Technology claims that the resulting battery provides four times greater surface area, is 30–50% smaller and lighter, and is 60 to 68% efficient than conventional lead-acid batteries.

Other companies such as Firefly Energy, a spin-off from Caterpillar, are also looking at the application of a lightweight, porous composite to replace the lead plates in conventional lead-acid batteries.

Firefly claims that its Advanced Battery technology can eventually remove approximately 70% percent of the lead from a traditional lead-acid battery design but still execute lead-acid chemistry for energy storage.

If that proves out, Firefly anticipates that it can deliver a jump in specific power, energy and cycle life approaching, but at about one-fifth the cost, of the present state of advanced material batteries such as NiMH and Lithium-ion.

(A hat-tip to Aaron Harvey!)

Resources:

Comments

Harvey D

What a surprise! After 150+ years somebody finds that lead acid batteries can be improved and could deliver the same power as NiMH and Li-Ion batteries. One could ask, why did it take so long to come up with what seems to be a common sense improvment? If this improvment materializes, a mid-size power pack for a PHEV could cost $4K instead of $20K. Secondly, lead acid batteries are inherently more robust and can be discharged and recharged more quickly. This would make PHEV more performant and much more economically competitive. A very interesting development.

Harvey D

What a surprise! After 150+ years somebody finds that lead acid batteries can be improved and could deliver the same power as NiMH and Li-Ion batteries. One could ask, why did it take so long to come up with what seems to be a common sense improvement? If this improvement materializes, a mid-size power pack for a PHEV could cost $4K instead of $20K. Secondly, lead acid batteries are inherently more robust and can be discharged and recharged more quickly. This would make PHEV more performant and much more economically competitive. A very interesting development.

Tripp

Perhaps this is the wrong place for this question but why does plugin technology raise the price of the vehicle by so much? Basically we're talking about ~$40K for a Plugin Prius vs ~$20K for a standard one. Is that correct?

Thanks,

Tripp

Jerry

Tripp, one reason might be the use of lithiums. From pricing them for my EV a pack of lithiums can easily run from $10-$30k. You also need specialized electronics to monitor and control the charge of each lithium cell.

On top of that I suspect whoever makes them would like a little profit...

-Jerry

http://www.evconvert.com/

Tripp

Good God, man. That's expensive! Still, Hybrids already have a battery pack in them that doesn't seem to jack the price up too much higher than a stardard vehicle. Is it because a much larger (meaning more stored energy) battery unit is installed in a PHEV?

Cheers,

Tripp

Engineer-Poet

That's exactly it.  A typical hybrid battery pack holds a little over 1 kilowatt-hour.  A PHEV battery pack for 10-20 miles of electric range is several times as big, and the small volume of production boosts costs further.

ChesserCat

First off, if you look at the chart in the actual article, you'll see that the NIMH battery is good for >500 charge cycles. That's if you deep discharge the battery. If you deep discharged the battery pack in a Prius, the pack wouldn't last a full year (assuming two charge cycles per day; it will probably have multiple such cycles in one hour of driving in traffic). Instead, they only discharge the battery pack about 20%. That means that you need a rather large battery pack (since you need 5x the energy you want to charge/draw in each cycle), but it also means that you get several thousand charge cycles out of it. That's enough to last for several years, providing a decent battery life.

Deeper discharge = fewer batteries needed for a given range. However, deeper discharge = fewer charge/discharge cycles.

Also, I've seen at least one article around here which says that the Japanese version of the Prius, which WILL run electric-only, can only go about 1.0 - 1.5 miles on the battery pack. This fits with Engineer-Poet's comment; if you want 10-20 miles of plug-in range, you will need a pack several times as large.

abdul jabbar

dear sir
i am dealing lead acid batteries.please send me your prices of these batteries.
6v 4.5a
12v 1.2a
12v 7a
12v 12a

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Your Information

(Name is required. Email address will not be displayed with the comment.)