Nitrate additives for lithium batteries: Mechanisms, applications, and prospects

Lithium-metal batteries (LMBs) are considered as one of the most promising energy storage devices due to the high energy density and low reduction potential of the Li-metal anode. However, the growth of lithium dendrites results in accumulated dead Li and safety issues, limiting the practical application of LMBs. LiNO3 is a well-known additive in lithium-sulfur batteries to regulate the solid-electrolyte interphase (SEI), effectively suppressing the redox shuttle of polysulfides. Recently, other nitrates have been investigated in various electrolyte and battery systems, yielding improved SEI stability and cycling performance. In this review, we provide an overview of various nitrates, including LiNO3 for lithium batteries, focusing on their mechanisms and performance. We first discuss the effect of nitrate anions on SEI formation, as well as the cathode-electrolyte interphase (CEI). The solvation behavior regulated by nitrates is also extensively explored. Some strategies to improve the solubility of LiNO3 in ester-based electrolytes are then summarized, followed by a discussion of recent progress in the application of nitrates in different systems. Finally, further research directions are presented, along with challenges. This review provides a comprehensive understanding of nitrates and affords new and interesting ideas for the design of better electrolytes and battery systems.