Sodium-Ion Solid-State Batteries: The Solution for Range and Cost Challenges

The production of batteries continues to be the priciest aspect of electric vehicle manufacturing. The challenges of obtaining raw materials, establishing supply chains, and constructing battery cell plants make it challenging for EVs to compete in pricing with traditional internal combustion engine (ICE) vehicles. Affordability remains the key obstacle to widespread EV adoption. While Tesla has pledged to launch a US$25,000 EV by 2025, it has not yet disclosed any details about such a vehicle or how it plans to maintain profitability at this price point.

Currently, lithium-ion is the dominant battery technology. In 2023, the cost of producing these batteries dropped by almost one-third due to a reduction in lithium prices, yet this decrease has not sufficiently impacted overall EV prices. Moreover, lithium production faces ethical sourcing dilemmas, particularly since a large portion of the world’s battery-grade lithium is sourced from the Democratic Republic of the Congo, where child labor remains a serious issue. Additionally, the lithium supply chain is susceptible to geopolitical tensions, especially with China, which controls much of the refining process and is currently in trade disputes with the US and EU.

Discovering alternatives to lithium-ion technology is crucial for Western automakers to manufacture EVs on a large scale at prices attainable for mainstream consumers. One alternative—sodium-ion—has been around for decades but has generally been regarded as suitable only for micromobility or stationary storage due to its relatively low energy density.

This perception may soon shift. TaiSan, one of the emerging start-ups focusing on sodium-ion technology, claims it can achieve an energy density of 300Wh/kg with its proprietary quasi solid-state sodium-ion battery. If successful, this could offer performance that surpasses most lithium-based batteries available today.

Addressing the Range Challenge

“Our aim is to enhance energy density, and sodium-ion is not yet adequate for EVs,” states Sanzhar Taizhan, Founder and CEO of TaiSan, in an interview with Automotive World. “Most automakers seek over 200Wh/kg, so we must advance the technology to make it commercially feasible.” While TaiSan has not shared the energy density figures for its first-generation prototypes, it is unlikely that these batteries have surpassed the necessary density for commercial viability. Nonetheless, Taizhan notes that advancements are happening more rapidly than initially anticipated.

As of now, JAC Yiwei, a Chinese automotive manufacturer, is the only company producing EVs equipped with sodium-ion batteries for consumers. Its Huaxianzi hatchback has been delivered to an undisclosed number of customers in China, with an additional 5,000 units planned for export to Latin America. The battery in this vehicle has an energy density of 140Wh/kg, which allows for a limited maximum range of 210 kilometers.

TaiSan believes ongoing improvements to its quasi solid-state technology will enable it to exceed 200Wh/kg and move closer to the targeted 300Wh/kg. The key distinction between its approach and conventional solid-state technology is the inclusion of a small quantity of liquid electrolyte alongside solid materials. “Standard solid-state batteries use ceramics, sulfides, or polymers, while our design incorporates a gel-type material,” explains Taizhan. “This enables us to retain the benefits of solid-state technology, like enhanced performance, while avoiding some of the associated drawbacks.”

This design helps reduce the formation of dendrites on the anode, which can cause short circuits. It also lowers the temperatures required for optimal ionic conductivity and decreases stacking pressure, resulting in a lighter battery. Most importantly, this innovation positions sodium-ion batteries to rival other technologies regarding driving range. While they might not completely match lithium- or nickel-based solid-state batteries, they can significantly close the performance gap compared to traditional liquid-based batteries.

Broader Implications

Closing this performance gap would be of limited benefit if there were no additional advantages to sodium-ion technology. From a consumer perspective, the primary advantage lies in cost savings. “To market a US$20,000 vehicle, you need a battery that costs no more than US$4,000,” Taizhan observes. “Automakers struggle to profit from cheaper models, which explains the prevalence of premium EVs.” TaiSan anticipates that its batteries will be approximately 20% less expensive than current alternatives when scaled to moderate levels.

The cost benefits primarily stem from sodium’s abundance compared to rare earth minerals like lithium. Sodium is about 1,000 times more plentiful in the Earth’s crust and more widely distributed. “Over 90% of natural sodium is found in the US, thanks to soda-lime glass production in the 1950s,” Taizhan points out. Conversely, much of Asia’s sodium production relies on coal, raising sustainability concerns. Establishing local supply chains for sodium batteries could be appealing for Western automakers and governments aiming to reduce dependence on China. These localized networks would also help eliminate ethical issues related to child labor in metal sourcing.

Moreover, sodium-ion technology may lead to reduced vehicle downtime. Although it has some limitations regarding energy density, sodium-ion batteries are capable of faster charging than their lithium-ion counterparts: the Huaxianzi hatchback can move from a 10% to 80% charge in under 15 minutes. Taizhan emphasizes that charging times could increase significantly in a solid-state configuration.

Building your own factory sounds appealing, but the cost makes it nearly impossible for us

Despite its potential, Taizhan cautions that sodium-ion technology remains largely untested at commercial scales. He believes in its viability but notes that TaiSan’s research and development efforts are still in their early stages. In July 2024, the company secured £1.3 million (approximately US$1.7 million) in funding to create prototypes—initially for internal testing and later for customers to evaluate. The company has also signed seven memorandums of understanding with battery manufacturers in anticipation of its solid-state technology receiving approval for commercial applications.

“While opening our own factory is a great concept, the financial reality presents significant challenges,” Taizhan concludes. “Our straightforward objective is to validate sodium-ion technology and then partner with existing production lines to help it enter the mainstream market.”