Embedded Files
15th December 2024
Sodium-ion batteries (Na-ion or SiBs) are a promising alternative to Lithium-ion (Li-ion) that may challenge their dominance in some applications. With the greater abundance of sodium and its lower cost relative to lithium, Na-ion batteries are competitive for stationary and grid-scale applications, even though they have a lower specific energy capacity. Further, the availability of sodium globally also presents additional environmental and socioeconomic benefits.
Can the safety of sodium cells surpass Li-ion? (Image by Allexxandar on Freepik)
However, there is a strong narrative that Na-ion batteries are safer than their Li-ion counterparts, but there is no clear evidence to back this up at the cell level. This is similar to the prevalence and common misunderstanding in the wider public that LFP cells are safe compared to NMC Li-ion cells, which led to an over-expectation of the safety of LFP battery systems and a lack of respect for their overall hazards at a system level. This should be taken as a lesson to accurately portray the threats of Na-ion batteries before their risks are underestimated.
Na-ion batteries are only in the early stages of commercialisation, which has limited publically available data. Only in the last six months has independent research been published assessing Na-ion thermal runaway behaviour. This evidence suggests that the current generation of Na-ion prismatic cells sits broadly between LFP and NMC cells on various thermal runaway quantities [1]. For cylindrical cells, Na-ion performs similarly to LFP cells [2]. However, the severity of thermal runaway of similar Na-ion cells is shown to vary significantly depending on the electrode material, electrolyte composition and manufacturer [3]. As we know from Li-ion batteries, not all cells are made equally and performance and safety can vary for similar types. From this, we can see the need for further studies and publication of openly available data on Na-ion cells to truly understand their failure behaviour over a broad range of different Na-ion cells (i.e. manufacturers, material compositions, etc.) and against Li-ion cells.
While Na-ion batteries offer substantial performance benefits (wider operating temperature, better charging rates and life span) we should not overly promote their safety without the evidence to back it up. With this, industry needs to lead the way with honest assessments of Na-ion abuse at a module and rack level to understand the thermal runaway propagation hazards i.e. thermal, fire, explosion and toxicity. The sodium-ion industry is in the fortunate position to learn from the two decades of lithium-ion battery safety research and prove itself to be less risky and more reliable.
[1] Li Z. et. al., "Thermal runaway comparison and assessment between sodium-ion and lithium-ion batteries", 2024, Process Safety and Environmental Protection, Vol 193, Pg.842-855
[2] Yue Y. et. al., "Thermal runaway hazards comparison between sodium-ion and lithium-ion batteries using accelerating rate calorimetry", 2024, Process Safety and Environmental Protection, Vol 189, Pg.61-70
[3] Bates A. et. al., "Multiscale Safety Evaluation of Sodium-Ion: Safer Than Lithium-Ion?", 2024, ECS PRiME Conference, Hawaii
Google Sites
Report abuse