Low Temperature Battery Design Shows Promise for Grid Energy Storage
New design lowers cost, improves system stability
To store energy for the grid, a handful of companies around the world manufacture sodium-metal halide batteries, known in the industry as ZEBRA batteries. Though currently the industry preference, challenges—including cost—impede their widespread use.
In a recent paper published in Nature Communications, PNNL researchers reveal a new intermediate temperature sodium-metal halide design that is more stable, less expensive to manufacture, and increases the battery’s energy density. The Department of Energy’s Office of Electricity Delivery and Energy Reliability and the Korea Institute of Energy Technology Evaluation and Planning supported the research.
The new design uses a very thin solid-state electrolyte plate made of a beta-alumina and yttria-stabilized zirconia composite—a ceramic. In contrast, ZEBRA sodium-metal halide batteries use a thick tubular shaped solid-state electrolyte made of pure beta-alumina.
Researchers conducted experiments on a button-sized battery from the new design. They found:
- its chemistry worked well at just 190 degrees Celsius—much cooler than the 280-320-degree range of its conventional cousin
- it maintained specific energy density of about 330 watt hours/kilogram, which is a much higher density than conventional batteries
- it remained very stable after more than 1,000 charge and recharge cycles at the time the paper was accepted
- its charging capacity didn’t degrade until the 700th cycle, and even then, it degraded only 0.01 percent per cycle
The new design could allow industry to make the battery with more conventional, less expensive seals, such as those made of a thicker, specialized polymer. In addition to being affordable, though, a stationary battery typically needs to withstand 3,000 – 5,000 cycles to be considered a viable energy storage option. Since the paper was accepted, the new battery design has surpassed 2,000 cycles and continues to operate.