Exploring Thermal Stability and Additive Performance in Lithium-Ion Electrolytes

Recent studies on lithium-ion battery electrolytes have provided intriguing insights into the thermal stability and effectiveness of various additives. This research primarily focused on mixed solvent electrolytes coexisting with lithium metal, revealing significant findings regarding their thermal behavior and cycling efficiency. Specifically, variations in the mixing ratio of solvents like 1M ethylene carbonate (EC) and dimethyl carbonate (DMC) were examined to assess their impact on lithium metal preservation.

One notable result indicated that adding certain additives could notably increase the onset temperature of the electrolyte system, thereby enhancing thermal stability. In particular, one additive emerged as the most effective in reducing exothermic energy, which can be crucial for maintaining battery safety and performance under thermal stress. The study employed differential scanning calorimetry (DSC) to estimate the content of surviving lithium metal based on the heat ratios observed during melting and freezing phases.

The research also highlighted the cycling efficiencies of different electrolyte compositions. For instance, the cycling efficiency of the single solvent electrolyte was found to be superior compared to mixed solvents, emphasizing the importance of careful formulation in achieving optimal performance. An interesting trend was that while some combinations, like EC+DMC, showed enhanced cycling efficiency with additive inclusion, others, such as the addition to propylene carbonate (PC), did not yield the same benefits.

Moreover, the conductivity of the electrolytes varied significantly depending on the additives used. The enhancements in conductivity were attributed to the lower viscosity of the effective additives, which in turn improved the ionic transport within the electrolyte. This finding showcases the critical role that solvent properties play in the overall efficiency of lithium-ion batteries.

The investigation also explored the effects of various organic additives, including polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP), on interfacial resistance. The results indicated that PEO stood out for its excellent performance in reducing resistance at the negative electrode interface, which is essential for efficient charge-discharge cycles.

Lastly, the research delved into the performance of different sulfite-based electrolytes, particularly at low temperatures. By incorporating compounds like ethylene sulfite (ES), the study revealed that PC-based electrolytes could effectively cycle with graphite anodes, overcoming previous limitations. This highlights the ongoing evolution in electrolyte formulation strategies aimed at enhancing the performance and safety of lithium-ion batteries across a range of operating conditions.