As heatwaves affected Europe this summer, demand for battery storage systems increased, prompting a US battery company to respond. San Diego-based Unigrid reported a rise in requests for its nine kilowatt hour sodium ion battery, which homeowners in Spain, France, Germany, and The Netherlands are seeking to store power from the grid at lower rates for use during peak air conditioning hours. Co-founder and CEO Darren Tan stated, "We have shipped the first 100 units and expect to ship 1,000 before the end of the year."
Unigrid's sodium ion battery technology is gaining attention due to its potential for lower production and operational costs compared to lithium ion batteries. These batteries are also considered to have a lower risk of catching fire and can operate in a wider temperature range, down to minus 40 degrees Celsius. However, there is ongoing debate regarding the optimal and safest design for sodium ion batteries, and several US companies in this sector have faced challenges in recent years.
Currently, China leads in sodium ion battery manufacturing, which presents a competitive challenge for US firms. Tan noted that while Unigrid's batteries currently use sodium ion cells sourced from China, there is potential for future sourcing from the US, albeit potentially at a higher cost.
Concerns have been raised regarding the use of chromium-3 in Unigrid's battery cathode, which under certain conditions could convert to chromium-6, a toxic substance. Prof Dame Clare Grey from the University of Cambridge cautioned against including materials that may raise safety concerns. Tan responded that toxicity concerns are exaggerated and emphasized that Unigrid's battery has passed safety certifications for the European market and is undergoing evaluations for the US market. Third-party tests have not demonstrated the formation of chromium-6 in their batteries.
The performance and longevity of sodium ion batteries are influenced by the choice of cathode material and electrolyte formulation. Some manufacturers are opting for alternatives to chromium, such as hard carbon or sodium iron phosphate pyrophosphate (NFPP).
The market for sodium ion batteries is evolving, with confidence in their reliability increasing. Last December, lithium iron phosphate (LFP) batteries were priced at $81 per kilowatt hour, while Unigrid's sodium ion batteries are priced around $100 per kilowatt hour. Some industry experts predict that sodium ion battery costs could eventually drop to as low as $30 per kilowatt hour, although analysts caution that such reductions may take years.
Sodium ion batteries are less energy-dense than lithium ion batteries, necessitating larger and heavier designs for equivalent power output. This technology is expected to be more suitable for larger energy storage applications rather than smaller devices like smartphones.
David Bell, co-founder and CEO of Emerald Battery Labs, expressed confidence that sodium ion technology could dominate 80% of the market. Emerald is currently developing 12-volt auxiliary batteries for vehicles, also utilizing China-sourced sodium ion cells.
Peak Energy, based in California and Colorado, has partnered with General Motors to develop a US supply chain for sodium ion batteries, aiming to establish a production facility in Michigan by the end of 2028.
The growing demand for electricity from data centers, which contribute to rising greenhouse gas emissions, presents an opportunity for sodium ion batteries to help distribute renewable energy more efficiently. ESS Tech, based in Oregon, is collaborating with Alsym to produce sodium ion batteries in the US, with plans to ship significant quantities by 2027.
While challenges remain in establishing mass production of sodium ion batteries, experts believe that successful firms could offer new strategic options for energy management, potentially reducing waste and keeping energy costs low.