An alternative for grid-scale energy storage, the sodium-ion battery

In the renewable energy industry, integrating energy storage is essential to address seasonal and intermittent variations in generation such as reduced solar output in winter or inconsistent wind supply. It also ensures the reliable delivery of power. Among the available options, electrochemical batteries quickly gained attention because they offered high efficiency, scalability, and compactness, making them suitable for both grid applications and consumer electronics (Dong, et al., 2024).

In the 1970s and 1980s, research into electrochemical energy storage solutions began, with sodium, lithium, and other elements investigated as potential charge carriers for these batteries. Because lithium-ion offered a high energy density, it was selected as the preferred charge carrier. Therefore, the alternatives were set aside in favour of further research and development of lithium-ion batteries (LIBs). In 1991, Sony launched the first commercialization of LIBs (Buonomenna & Bae, 2017). Today, LIBs are found in nearly every type of electronic battery application, from smartphones to electric vehicles (EVs) and grid storage.

With a mature manufacturing infrastructure, LIB manufacturers have made significant progress in enhancing performance and reducing costs. Modern LIBs exhibit low self-discharge rates (~1.5% per month) and a long cycle life of 500–1000 cycles (Pilali, et al., 2025). The cost of LIBs has fallen dramatically, from around US$7,500/kWh per cell in 1991 to approximately US$120/kWh per pack in 2025 (Ritchie, 2021). Although LIBs offer many benefits, they also exhibit drawbacks that make them a less favourable option for energy storage. The reduction in cost to around US$120/kWh is impressive, but LIBs remain relatively expensive, particularly for utility-scale projects where developers aim for substantially lower prices to ensure economic viability. In addition to cost, the growing global demand for lithium creates supply constraints and price volatility, while extraction and processing can have environmental impacts. Recycling LIBs also remains technically challenging and expensive, further limiting their long-term sustainability. This highlights the need for alternative, more sustainable battery chemistries.

The financial aspect is a critical factor for project developers in determining whether a project is viable. Due to the high cost and limited availability of lithium, manufacturers and developers have been compelled to seek alternatives that not only reduce costs for consumers but also provide energy storage solutions that are more sustainable and environmentally friendly.

Today we can’t only care about high performing batteries but need to think about it holistically. We need to consider how we can create cost-effective and sustainable solutions in order to get energy to all without compromising the future of this planet. Thus, the focus would lie in a low cost, high performing energy storage system with effective recycling processes in place.

Sodium-ion batteries (SIBs) have been considered a promising next-generation alternative due to their widespread availability and their chemical similarity to LIBs (Gao, et al., 2023). In recent years, SIBs have gradually resurfaced as an optimal replacement for LIBs. The raw sodium material used in SIBs is about 30% cheaper than lithium, making them less costly to produce overall. SIBs are currently priced between $75–$100 per kWh at the pack level (IDTechEx Ltd, 2024), depending on chemistry and scale. This makes SIBs a more affordable option compared to LIBs which, yet again, are priced around $120/kWh at the pack level. This is noteworthy for utility-scale projects where cost-effectiveness is of the utmost importance. Furthermore, SIBs are easier to source, present a lower environmental risk, and offer a longer cycle life, typically ranging from 2,000 to 4,000 cycles (Pilali, et al., 2025). Moreover, because SIBs share similar chemistry with LIBs, making it possible to leverage much of the existing LIB manufacturing processes, however, materials, supply chains, and quality control may require adaption.

SIBs have been proven in the field, making them more than a theoretical solution. From an early experimental trial of a 100 kWh Na-ion battery which was launched in 2019 (Chinese Academy of Science, 2019) at the Yangtze River Delta Physics Research Centre in Liyang city, China, to the first grid-scale installation of a 200 MWh Na-ion battery in Nanning, China. This installation was commissioned by the Chinese Southern Power Grid Energy Storage (CSG) company in 2024 (Green Building Africa, 2025), which forms part of a hybrid lithium-sodium battery with a capacity of 400 MWh. These real deployments demonstrate feasibility at both pilot and utility scales, underscoring that the remaining questions related to performance trade-offs, bankability, and system-level constraints.

Although SIBs offer several benefits, they also exhibit drawbacks, but their main challenge lies in energy density, typically 100-160 Wh/kg compared to 180-250 Wh/kg for LIBs such as lithium-ion and lithium iron phosphate batteries. The lower energy density makes SIBs less suitable for applications where compact size is critical, such as consumer electronics (e.g. smartphones) and electric vehicles (EVs). However, because the renewable energy sector does not face the same size constraints SIBs represent a highly viable solution for stationary energy storage in this field. Another disadvantage SIBs have compared to LIBs is their self-discharge rate. LIBs currently achieve around 1.5% per month (UoW – CEI, 2025), slightly lower than the rate of 2–3% per month seen in SIBs (Erik, 2023). However, as SIB technology is still in its early stages, further research will likely bring this rate down, potentially below that of LIBs.

LIBs remain the leading energy storage technology due to their high energy density, low self-discharge rate, and reliability. However, the high cost and limited availability of lithium make them less sustainable in the long term. SIBs present a promising alternative, offering affordability and resource availability that position them well for grid-scale applications.

Going forward, LIBs are likely to retain dominance in portable electronics and high-performance EVs, while SIBs are expected to excel in stationary energy storage. Together, these technologies will serve complementary roles in advancing sustainable and cost-effective energy solutions for the future.

To highlight the strengths and drawbacks between lithium-ion (LIB) and sodium-ion (SIB) batteries, the table below represents a side-by-side comparison of key specifications between these two battery chemistries.

References:

• Buonomenna, M. G. & Bae, J., 2017. Sodium-Ion Batteries: A Realistic Alternative to Lithium-Ion Batteries?. Nanoscience and Nanotechnology – Asia, pp. 139-154.
• Chinese Academy of Science, 2019. China First Demonstrates the 100 kWh Na-Ion Battery System for Energy Storage, Beijing: Chinese Academy of Science.
• Dong, Z., Li, L. & Li, Y., 2024. The problems with solid-state sodium ion battery electrolytes and their solutions, China: EDP Sciences.
• Erik, 2023. Sodium Ion vs Lithium Ion Batteries. [Online] Available at:
  https://www.offroadchampions.com/blogs/sodium-ion-vs-lithium-ion-batteries/ [Accessed 1 October 2025].
• Gao, Y. et al., 2023. A 30-year overview of sodium-ion batteries, s.l.: Wiley.
• Green Building Africa, 2025. First large-scale hybrid lithium-sodium battery energy storage facility commissioned in China. [Online] Available at:
  Green Building Africa
• IDTechEx Ltd, 2024. Sodium-ion Batteries 2024–2034: Technology, Players, Markets, and Forecasts, s.l.: IDTechEx.
• Pilali, E. et al., 2025. SWOT analysis on the transition from Lithium-Ion batteries to. Elsevier, pp. 1–16.
• Ritchie, H., 2021. The price of batteries has declined by 97% in the last three decades. Our World in Data.
• UoW – CEI, 2025. Lithium Ion Battery. [Online] Available at:
  https://www.cei.washington.edu/research/energy-storage/lithium-ion-battery/