Long-duration liquid metal battery passes key safety certification


Ambri, developer of long-duration liquid metal batteries, announced its battery product has achieved UL 1973 certification. The key safety certification approves the batteries for stationary and motive auxiliary power applications.

Ambri, spun out of the Massachusetts Institute of Technology (MIT), secured a $144 fund in 2021 to develop and scale its long-duration energy storage (LDES) technology. LDES is actively being researched and developed globally for its ability to support the intermittent generation cycles of renewables like PV and wind.

“The certification marks a major milestone for the commercialization of our Liquid Metal battery technology, by giving the seal of approval that our next generation, double capacity cells meet the highest safety standards,” said David Bradwell, chief technology officer and co-founder at Ambri.

The liquid metal battery is comprised of a liquid calcium alloy anode, a molten salt electrolyte, and a cathode comprised of solid particles of antimony, enabling the use of low-cost materials and a low number of steps in the cell assembly process.

The company said that the active materials in its cells reversibly alloy and de-alloy while charging and discharging. The electrolyte is thermodynamically stable with the electrodes, avoiding side reactions that can lead to performance degradation. The negative electrode is fully consumed when discharged, and reformed on every cycle, resulting in what the company said is a “highly repeatable process with no memory effect.” Designed for daily cycling in harsh environments, the battery has an expected lifetime of 20+ years with minimal fade, said Ambri.

Ambri said its batteries are made with commonly available, commercial-grade raw materials. Grid-scale storage alternatives to lithium and cobalt batteries are targeted due to concerns about conflict mineral human rights issues, high demand for the material, and problems with thermal runway or fires.

Image: Ambri

Ambri announced a collaboration with utility Xcel Energy to be the first grid operator to deploy its battery. It will install a 300 kWh system jointly tested at SolarTAC in Aurora, Colorado over a 12-month period.

The battery system incorporates Ambri’s liquid metal battery cell, which the company said more than doubles its previous energy capacity cell. The system is expected to become fully operational by 2024 and will use the GridNXT Microgrid Platform to facilitate the utilization of multiple generation sources like solar and wind along with inverters, load banks and three-phase distribution connections and communications.

“Our recently announced collaboration with Xcel Energy will showcase the high-performance of this next generation cell and sends a message to the industry that our technology is advancing to meet market and customer demands without compromising on safety and reliability,” said Bradwell.

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