Zinc bromide batteries get US government help to scale up

A new facility will be able to produce battery capacity to power 130,000 homes on a daily basis using renewable energy.
Ameya Paleja
Stock image of battery energy storage for a solar power plant
Stock image of battery energy storage for a solar power plant


Zinc halide batteries touted as a low-cost alternative to battery energy storage system (BESS) have received a significant boost in the US after the Department of Energy (DOE) offered a $400 million loan to help scale production and reduce manufacturing costs, a press release said. The offer will cover setting up of four production lines at battery maker Eos' facility in Turtle Creek, Pennsylvania.

Lithium-ion batteries are a crucial component of our attempts to switch to a greener economy powered by renewable energy. Although the technology is ubiquitous these days and powers everyday devices like smartphones and even electric vehicles (EVs), it is still very expensive.

As demand for lithium grows, costs could go further upwards, making it economically unfeasible to shift to renewables whose intermittency demands significant energy storage mechanisms that can prevent the grid from collapsing when energy production drops.

Zinc Bromide batteries to the rescue

In zinc bromide batteries, the cathode is made using zinc instead of lithium, the fourth most produced metal in the world. The electrolyte is water-based and, therefore, does not pose a fire risk.

The technology has existed for more than five decades after researchers at Exxon patented it in the 1970s. In the past decade, companies like Eos have developed them further, bringing them closer to mass adoption.

Eos contribution includes 6,000 charge/ discharge cycles, which means that the batteries can be used for a good 20 years, as against the 10-15 years Lithium-ion batteries last. Also, zinc batteries do not need support like active temperature control while working.

Zinc bromide batteries get US government help to scale up
Illustration of the zinc battery with bipolar electrodes (1), aqueous electrolyte (2) and polymer casing (3)


DOE Support for manufacturing

EOS's current facility in Pennsylvania has a production capacity of 540 megawatt-hours, sufficient to power about 7,000 electric vehicles annually. The DOE's Loan Programs Office (LPO) has now approved a $398.6 million loan guarantee to enable the company to build four state-of-the-art production lines for its latest generation zinc bromide batteries.

When complete, these production facilities will enable the storage of eight GWh of electricity annually by 2026. This capacity will be able to meet the energy demands of 130,000 homes if charged and discharged on an everyday basis, the press release said.

The loan guarantee is conditional, and Eos must meet critical milestones about the technical capabilities of the battery in development, as well as legal and financial conditions set for the manufacturer before the funds are allotted.

Among the technical issues the zinc bromide battery faces is relatively low efficiency. This translates to larger energy losses during charging and discharging when compared to lithium-ion batteries. Unwanted chemical reactions occurring inside the battery can also severely shorten its lifespan, MIT Technology Review said in its report.

Experts are of the view that the technical challenges can be overcome. Eos' major challenge will be demonstrating that the battery can be manufactured at a large scale and low cost.