Review of electrolyte strategies for competitive dual-ion batteries

The development of potential substitutes for lithium-ion batteries has attracted considerable attention in recent years due to the scarcity of lithium sources and the urgent demand for energy storage systems. Remarkably, dual-ion batteries (DIBs) based on a particular intercalation mechanism of anions exhibit great promise as next-generation batteries with high operating voltage, low cost, and high safety. However, research on DIBs is still in its infancy, and many fundamental issues, such as limited energy density, structural failure, sluggish kinetics, and electrolyte deposition, must be understood more comprehensively to explore high-performance electrolytes and electrodes and establish stable redox electrochemistry. In this review, we summarize the current mechanisms and challenges of DIBs to address and alleviate these issues. Among various critical components of DIBs, electrolytes are receiving considerable attention because they provide the basic operating environment and participate in the energy storage process. Several electrolyte strategies, including high-concentration, hybrid ion, functional additive, and solid-state strategies, have been proposed. These strategies have been demonstrated to not only improve the properties of electrolytes, but also to deliver superior battery performance. Therefore, a comprehensive overview of electrolyte strategies is presented and discussed in detail for the future development of DIBs.