Science Vertical III

Due to the limited availability of lithium resources and concerns related to their sustainability, sodium-ion batteries have become an excellent candidate for applications such as stationary grid storage. Sodium-ion batteries offer various advantages, including the high abundance, low cost, and redox potential of sodium. Based on various aspects such as desolvation energies, coordination preferences, solid electrolyte interphase characteristics, and electrolyte interactions, sodium-ion chemistry can fundamentally differ from its lithium-ion counterpart.

In addition, the role of cathode/anode microstructure, pore-scale attributes, and electrolyte transport on the electrochemical performance, degradation, and safety in sodium-ion batteries will be distinct. Through this science vertical, the fundamental kinetic-transport interactions in sodium-based electrode microstructures, electrode-electrolyte interactions, and their implications on safety science in sodium-ion batteries will be comprehensively studied. With respect to the cathode, similar to lithium-ion batteries, highly reversible cathode materials based on intercalation reactions are required to achieve high capacity and stability in sodium-ion batteries.

Due to the larger size of sodium ions, structural changes due to ion intercalation in the host are more prominent. The role of such geometric deformations of electrode materials on the kinetics of electrochemical reaction, transport, and mechanical stress distribution within the electrode architecture will be investigated. Concerning the anode, various candidates including carbonaceous materials, transition metal oxides, and intermetallic and organic compounds have been studied for sodium-ion chemistry.

Based on this, the underlying reaction mechanism is governed by insertion, conversion, or alloying. While conversion and alloying-based anode materials can deliver higher capacities, the large volume expansion of the host material can result in electrochemical-mechanical instability and pose a major limitation. Based on the nature of salts, solvents, and additives, the role of electrolyte properties including chemical, electrochemical, and thermal stability, and ionic transport on electrochemical performance and safety will be studied in this science vertical. For sodium-based electrodes, the chemical composition and underlying heterogeneity of the solid electrolyte interphase is another aspect that affects the degradation-safety response.

Overall, the mechanistic interaction in sodium-ion batteries including the electrode microstructure, electrochemical-mechanical characteristics of interfaces, and electrolyte-mediated interactions, and their implications on safety will be analyzed.