Sodium-ion based battery technologies: An alternative to existing solutions

Energy storage technologies, like sodium-ion batteries, based on abundant metals, offer an exciting opportunity for India, which does not have any viable domestic reserves for the currently dominant lithium-ion batteries.

Energy storage technologies are expected to play a critical role in India's energy transition. From powering electric vehicles to integrating renewable energy in the grid, the technology can support a wide range of applications. Of late, sodium-ion batteries are gaining traction as an alternative to the currently prevailing lithium-ion batteries. Before the Indian industry further invests in this technology, it would be prudent to examine advantages, identify appropriate applications, and secure supply chains for domestic manufacturing.

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Rethinking the global trends

Today, the global storage market is dominated by three lithium-ion batteries: Nickel Manganese Cobalt oxide (NMC), Lithium Ferro Phosphate (LFP), and Lithium Titanium Oxide (LTO). High energy and power density along with greater efficiencies of charge-discharge cycles, which allow usage across applications, are the key advantages offered by lithium-ion batteries. Several gigawatt-scale lithium-ion battery manufacturing plants are currently operational in few countries which cater to the global demand. However, excessive reliance on lithium-ion batteries exposes countries like India to geopolitical supply chain risks as domestic reserves for key constituent minerals like lithium, cobalt, and nickel haven't been identified. Almost 57 per cent of world lithium reserves are located in Chile. Similarly, Democratic Republic of the Congo accounts for 49 per cent of the world's cobalt reserves. Any disruption in these economies or imposition of export bans could disrupt the supply chain for the domestic manufacturing industry. The Covid-19 pandemic has already exposed the vulnerability of heavily relying on a particular technology or a specific technology provider.

Furthermore, some of these technologies might not be suitable for the Indian climatic conditions, which vary across the country, increasing the possibility of accidents. Due to these challenges and limitations, one needs to also look for alternative solutions to lithium-ion based batteries which can meet India's storage needs in a sustainable manner.

Alternatives galore

Among many others like metal-air and redox flow, sodium-ion batteries are gaining popularity as a potential alternative to lithium-ion batteries. There are several reasons for this emerging trend. First, sodium is an abundant metal which offers a strategic advantage for the country, given India is a global leader in the production of salt (sodium chloride). Local availability of the raw materials would ensure a secure supply chain for battery manufacturing.

Secondly, the working principle of these batteries is very similar to lithium-ion batteries. This means the existing lithium-ion battery manufacturing plants can be retrofitted to manufacture sodium-ion batteries. Thirdly, sodium-ion batteries have a wider operational temperature range than lithium-ion batteries which makes them suitable and safe for operations in extreme weather conditions. Lastly, on the technical parameters, the energy density of available sodium-ion battery from leading technology providers is competitive, albeit smaller, to lithium NMC variants.2 Despite the lower energy densities, sodium-ion batteries provide a good value proposition for stationary storage applications where energy density is not a priority. Some of these applications include behind-the-meter storage at the consumer end and power backup for telecom towers and data management centres. Furthermore, sodium-ion batteries allow fast recharging up to full capacity. This is a massive advantage over other technologies where safety issues can limit fast recharging capabilities. These combined advantages of cost, availability, safety, and superior performance metrics make sodium-ion batteries a lucrative choice for decision-makers.

What is a Sodium-ion battery

However, just like any other technology, sodium-ion batteries come with their own share of challenges. These batteries have a higher self-discharge than lithium-ion batteries. When not in use, sodium-ion batteries lose considerable amount of the stored energy, resulting in a shorter shelf life. Furthermore, the stability of the electrolyte in these batteries is low. Migration of sodium-ions during charge-discharge cycles ruptures the non-flammable solid electrolyte, thereby damaging the battery. Extensive research to overcome these shortcomings is being undertaken and hopefully future advancements would allow efficient utilisation of this technology.

Seize the opportunity

Until now, most of the focus has been on batteries based on lithium-ion technologies, but now new and alternative technologies like sodium-ion are being manufactured at scale. In a welcome development, the UK-based company Faradion is planning to establish the first sodium-ion battery manufacturing plant in India by 2021. The National Mission on Transformative Mobility and Battery Storage proposes a technology-agnostic approach for battery manufacturing. Indian companies should take advantage of this and collaborate with technology providers, scale-up manufacturing, and conduct pilot demonstrations for establishing a viable use case. Leveraging developments in technology and regulatory aspects can increase self-sufficiency in this sector from the start. As the Indian economy prepares to revive from the repercussions of Covid-19, clean energy technologies like battery manufacturing could provide an excellent opportunity to boost domestic value addition, create employment opportunities, and ensure sustainable development.