Household bleach more than doubled the output of a saltwater grid battery

Engineers at the U.S. Department of Energy’s Oak Ridge National Laboratory have found that leaning into a common household-bleach reaction, rather than fighting it, can more than double the peak power of a saltwater battery built for grid-scale energy storage. The result, published by the laboratory on September 1 and updated two days later, comes from lab test cells developed with industry partner Coulomb Technology, not from a battery pack running on the grid. It is an early but notable step for a battery chemistry that avoids the lithium and cobalt supply constraints of today’s grid storage banks, part of a broader effort at the laboratory to help utilities meet rising electricity demand, cut storage costs, and keep power flowing during outages.

Why saltwater batteries have lagged behind lithium-ion

Most grid-scale storage today relies on banks of lithium-ion cells, the same basic chemistry used in electric vehicles, scaled up. They require active cooling to limit fire risk and depend on lithium and cobalt that are largely imported. Saltwater batteries have long been pitched as an alternative: salt water is cheap, widely available, naturally cooling, and free of the critical-materials problem entirely. The catch is that conventional saltwater batteries rely on a sluggish oxygen reaction that shuttles between liquid and gas states, a process that needs a catalyst, consumes extra time and energy, and caps how much power the battery can deliver on demand. That tradeoff is a major reason saltwater chemistries have stayed a research curiosity rather than a mainstream option for utilities, even though the raw material itself costs almost nothing.

A reaction usually suppressed becomes the main event

ORNL researchers, led by Ruhul Amin and postdoctoral researcher Wooseok Go, were trying to improve that oxygen reaction when they noticed a separate, faster reaction happening just before it: one that produces sodium hypochlorite, the active ingredient in household bleach. Battery designers typically treat this side reaction as something to minimize. Go’s team instead asked why not let it dominate, since it already produced a higher voltage than the oxygen reaction it was competing with. Adding just 5 percent more bleach to the electrolyte was enough to make the chlorine-based reaction take over. The mechanism relies on a reversible chemical cycle that toggles between chloride and hypochlorite ions as the battery charges and discharges, rather than on the gas-forming oxygen step the team had originally set out to fix.

An all-liquid reaction removes two bottlenecks at once

Because the chlorine-bleach reaction happens entirely in liquid form, the battery no longer needs the gas-conversion step or the catalyst the oxygen reaction required, and its internal resistance dropped as well. Together those changes more than doubled the cell’s peak power output and pushed its voltage close to lithium-ion levels, according to the laboratory. Amin described the difference as akin to swapping a family sedan for a sports car: the battery can deliver a burst of power quickly and hold it steadily, which matters most during an outage, when the grid needs power immediately rather than gradually. Ilias Belharouak, who heads ORNL’s electrification section, also contributed to the project, which the laboratory frames as part of a wider push to diversify grid storage beyond lithium-ion.

What was actually measured, and what remains untested

The laboratory’s account describes a comparative result from test cells built and cycled inside ORNL’s Battery Manufacturing Facility: adding bleach roughly doubled peak power output and raised voltage relative to the unmodified saltwater chemistry. It does not report a specific power or energy capacity in kilowatts or kilowatt-hours, a cycle-life figure, or any data from a battery operating on an actual grid or in a data center. Peak power, the metric the laboratory highlighted, describes how fast a battery can respond to a sudden spike in demand; it is a different measurement from total energy capacity, which determines how long a battery can keep supplying power once it starts discharging, and that second figure is not addressed in the release. Saltwater cells are also bulkier and heavier than lithium-ion for the same output, which is why researchers are pitching the chemistry for stationary storage rather than vehicles or portable electronics. ORNL says the next phase of the work involves changing the battery’s anode metal and further suppressing the original oxygen reaction, meaning the chemistry is still being refined rather than finalized. None of that changes the core finding, but it does mean the version described this week is a proof-of-concept chemistry rather than a finished product ready for a utility to order.

A path toward commercial deployment, not yet a deployment itself

The research was carried out with Coulomb Technology, a Tennessee-based startup that builds sodium-ion batteries for grid applications and whose founder came through ORNL’s Innovation Crossroads fellowship program for energy startups. The company says the bleach-boosted chemistry could round out its lineup for longer-duration utility and data-center storage, and potentially for ships, which carry their own steady supply of salt water. Coulomb has not announced an installed project or a timeline for one; its stated plans remain to commercialize the technology, funded in part through the Department of Energy’s Technology Commercialization Fund. Until a version of the battery is built and tested at real grid scale, the doubled output remains a laboratory finding rather than a proven grid capability, even as the underlying chemistry gives grid planners another low-cost option to weigh against lithium-ion as demand for storage keeps climbing.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

More from Morning Overview