Aging Diagnostics for a Commercial Sodium-ion Cell: Experimental and Simulation-based Transfer from Lithium-ion Systems

Sodium-ion batteries are gaining attention as a cost-effective and sustainable complementary technology to their lithium counterpart. However, fully realizing their drop-in potential and integrating them into applications requires a deeper understanding of their aging behavior, as well as the implications for the overall system. A high-power, cost-sensitive application is selected, where lithium-ion cells could potentially be replaced by a cheaper complementary technology with similar power characteristics and energy density. An extensive field dataset from this application is then analyzed to determine the operational requirements that such a technology must meet in terms of lifetime and management. Following this analysis, a unique aging study on sodium-ion cells with layered-oxide cathode and hard-carbon anode is conducted. The results show that while there are distinct aging patterns in the sodium-ion cells, the lifetime is high with an average capacity loss of 2.8% after approximately 4000 equivalent full cycles across different operating conditions. The parameterized models, derived from the experimental data, and application-specific requirements are implemented in a simulation framework to evaluate real-time algorithms commonly used for lithium-ion batteries. We analyze that the favorable voltage range and steep open-circuit voltage curve of the investigated sodium-ion cells allow the use of simpler models and lower-cost sensors without affecting algorithm performance. By quantifying degradation and algorithm performance, this work guides the integration of sodium-ion batteries into applications, shortening the time to market for these technologies as viable alternatives to lithium-ion batteries when economic or political factors make it necessary.