Weak Solvent-Solvent Interaction Enables High Stability of Battery Electrolyte

Electrolytes play an important role in transporting metal ions (e.g., Li+) in metal ion batteries, while understanding the relationship between the electrolyte properties and behaviors is still challenging. Herein, we detect the existence of weak solvent-solvent interactions in electrolytes by nuclear magnetic resonance (NMR), particularly discovering that such interactions have a significant function of stabilizing the electrolytes, which has never been reported before. As a paradigm, we renovated the understanding of the role of ethylene carbonate (EC) solvent in the lithium-ion battery electrolyte. We find that the EC solvent can stabilize the linear carbonate solvent electrolyte, particularly the diethyl carbonate (DEC) electrolyte, by the weak intermolecular interactions, enhancing the energy difference between the orbitals of the Li+(EC)(x)(DEC)(y) complex, in turn demonstrating strong capability against reduction. Our viewpoint was further demonstrated in other metal ion batteries (e.g., Na+, K+), whose discovery is significant for designing electrolytes and in-depth understanding of the battery performance.

Automated summary

We detected the presence of weak solvent-solvent interactions in electrolytes using nuclear magnetic resonance and found that these interactions play a significant role in stabilizing the electrolytes, which is a novel discovery. By studying the role of ethylene carbonate (EC) solvent in lithium-ion battery electrolyte, we found that EC can stabilize linear carbonate solvent electrolyte, particularly diethyl carbonate (DEC), through weak intermolecular interactions, enhancing the energy difference between the orbitals of the Li+(EC)(x)(DEC)(y) complex and demonstrating strong capability against reduction. Our findings were further confirmed in other metal ion batteries (e.g., Na+, K+), highlighting the importance of electrolyte design and deeper understanding of battery performance.