An industrial pathway to emerging presodiation strategies for increasing the reversible ions in sodium-ion batteries and capacitors

Abstract

Sodium-ion batteries (SIBs) and capacitors (SICs) have been drawing considerable interest in recent years and are considered two of the most promising candidates for next-generation battery technologies in the energy storage industry. Therefore, it is essential to explore feasible strategies to increase the energy density and cycling lifespan of these technologies for their future commercialization. However, relatively low Coulombic efficiency severely limits the energy density of sodium-ion full cells, particularly in the initial cycle, which gradually decreases the number of recyclable ions. Presodiation techniques are regarded as effective approaches to counteract the irreversible capacity in the initial cycle and boost the energy density of SIBs and SICs. Their cyclic stability can also be enhanced by the slow release of supplemental sodium and high-content recyclable ions during cycling. In this review, a general understanding of the sodium-ion loss pathways and presodiation process towards full cells with high Coulombic efficiency is summarized. From the perspectives of safety, operability and efficiency, the merits and drawbacks of various presodiation techniques are evaluated. This review attempts to provide a fundamental understanding of presodiation principles and strategies to promote the industrial development of SIBs and SICs.