RSR reveals lead alloy ‘game-changer’ versus lithium

RSR reveals lead alloy ‘game-changer’ versus lithium

RSR reveals lead alloy ‘game-changer’ versus lithium 200 200 Batteries International

13 September 2018: A ground-breaking lead alloy developed for the active material of lead acid batteries by RSR Technologies with the aid of real-time X-ray imaging technology has gone into commercial production at the South African battery firm Auto-X, the maker of the Willard brand of batteries following tests that show it doubles the cycling life of lead batteries.

Speaking to BESB, manufacturing and technical director Kelvin Naidoo said the results were ‘spectacular’, and had shown vastly improved cycling and greatly reduced water loss — the holy grail for lead batteries.

The breakthrough Supersoft-Hycycle material contains an engineered suite of micro-alloying additions, which enhance the cycling and charge acceptance of the active material in a lead acid battery, said RSR president Tim Ellis (pictured).

The effect of the proportions of the micro-alloying additions on the micro-structure of the active material were determined with the use of an Advanced Photon Source synchrotron, which is housed at the Argonne National Laboratory (ANL) and is used in a huge range of scientific disciplines.

Scientists have been able to watch the performance and evolution of the active material micro-structure in the batteries as they cycled in real time by using the APS synchrotron, allowing far more accurate analysis of the dynamics of crystallization phenomena occurring in the battery during charge/discharge cycling.

How and why crystals do or do not dissolve is key to improving performance in applications.

“Lithium has used the APS synchrotron to make advances, but no one has tried it with lead,” said RSR Technologies’ president Tim Ellis.

“We talked to the ANL people and they welcomed the idea of looking at lead because they haven’t had much exposure to it before — they looked at some of the data and said they would like to work on the PbSO4 to a more easily dissoluble crystal form — thus prolonging battery life.”

In the laboratory experiments that followed, when the Supersoft-Hycycle alloy was placed against a ‘control’ lead element typical of standard lead batteries, the careful selection of micro-alloying additions and removal of specific contaminants were found to directly aid in changing the PbSO4 to a more easily dissoluble crystal form — thus prolonging battery life.

Auto-X has been trialling the technology from day one, using it as standard in its products while tests were being carried out.

It tested a 12V battery using Supersoft-Hycycle combined with 009, a grid alloy engineered for higher use temperatures also developed by RSR Technologies following a long history of development by David Prengaman.

The battery achieved more than double the number of cycles achieved by the control lead material using standard industry testing protocols, thanks to the retardation of Ostwald ripening and other failure mechanisms.

“We’ve been through the journey with them,” said Auto-X’s Naidoo. “Our problem has always been corrosion on the positive plate. It’s not a problem any more. We are getting results that we can’t understand because we expect there to be a failure amount and we’re not getting one at all.

“In Africa with the high temperatures you expect grid corrosion and we’ve just tested some imported batteries in the field, which all failed. But this alloy is performing remarkably well.”

Naidoo says he expects the new material will prove to be a spectacular game changer for the lead battery industry.

“The cyclability test is based on a specification of a 17.5% depth-of-discharge, and you would normally see a cycle rate of between 800 and 900,” he said.

“Using the RSR alloy we did in excess of 1,200 cycles — up to 1,600 cycles.

“It’s only just now being marketed, but for us it’s already standard. It was a game changer to us — and I believe there’s still more development that will follow.”

“Lithium has always had great cycling and great energy but higher cost and nowhere near the recyclability of lead,” said Ellis.

“Lead is less expensive and more recyclable but didn’t have the energy or the cycling. Now it can maintain its low cost and improve its cycling and energy as well.

“Ten years ago, when car manufacturers started rolling out micro-hybrids, everyone said we can remove the lead and replace it with lithium — but it hasn’t happened on a great scale. Every Tesla has a lead starter battery. Electrified HEV, PHEV and BEV vehicles are way off main stream — they are still just 3% of the market.”