Sodium-ion batteries (SIBs) are a promising alternative to state-of-the-art lithium-ion batteries (LIBs). They are particularly beneficial as low-cost alternatives using more abundant resources that can be obtained from less critical economic, social and environmental sources . The energy density of SIBs can be significantly higher than lead-acid or nickel metal hydride batteries, while being close or even on-par with some LIB cell chemistries . Moreover, SIBs can be assembled using LIB production lines, which means that the manufacturing processes are already accessible at industrial scale . To reach a competitive level, however, progress in materials development and cycle life are still the most urging SIB research topics.