1,3,2-Dioxathiolane 2,2-Dioxide as a Bifunctional Electrolyte Additive to Enhance the Stability of Lithium Metal Anodes

Rechargeable Li-metal batteries (LMBs) are regarded as the future generation of prospective high-energy rechargeable battery systems. However, the strong reactivity of the Li metal is highly likely to cause side reactions with electrolytes, resulting in low coulombic efficiency (CE), and Li dendrite growth is the culprit of safety concerns. In this work, we report on a new approach utilizing 1,3,2-dioxathiolane 2,2-dioxide (DTD) additives in electrolytes to enhance the performance of LMBs. The mechanisms of the DTD molecule were investigated in detail using mass spectral titration, molecular dynamics simulations, and in situ optical microscopy. In general, the DTD molecule not only changes the Li-ion solvation structure but also optimizes the SEI component, which decreases the energy barrier for Li deposition and reduces the generation of "dead Li". As a result, the deposition morphology of Li was totally changed, and the growth of Li dendrites was effectively suppressed. Electrochemical tests showed that the average CE of the Li||Cu half-cells was improved from 71.0% for 60 cycles to 95.8% for 275 cycles after the introduction of 5.0 wt % DTD in the carbonate electrolyte. Moreover, the Li||Li symmetric cell and the Li||NCM811 full cell exhibited significantly enhanced cycling stability.