Structural Designs for Accommodating Volume Expansion in Sodium Ion Batteries.

Abstract: At the forefront of energy storage field, developing sodium ion batteries (SIBs) has drew a wide concern due to relatively low cost and abundant resource, comparing with lithium ion batteries (LIBs). Serious volume expansion constraints the electrochemical performance of the conversion/alloying materials, despite of their high reversible capacities or theoretical capacities. Here, from the perspective of structural designs, we systematically study four types of routes to accommodate volume expansion. Delicate and peculiar nanostructures based on nanocrystallization engineering are widely focused on, covering nanosheet assembly and nanoarray construction. Robust materials such as carbon‐based materials can be utilized as the buffer matrix, mitigating the mechanical stress during the charge/discharge process. Besides, recent studies have demonstrated void space reservation in nanostructures was also beneficial for adapting to volume changes. Moreover, for conversion materials, numerous works have confirmed the advantageous influence of interlayer spacing regulation. We also explained the superiority and challenges for further giving scope to structural designs. Sketching out the future studies in SIBs, in situ characterizations are supposed to be highlighted, as well as in‐depth researches on the stress evolution caused by volume expansion. [ABSTRACT FROM AUTHOR]