Performance Evaluation and Analysis of Rolechem's ARC-S35 Fluorosulfonate Compound

Rolechem has launched its new additive, ARC-S35, which is a sulfonate compound. Through three core mechanisms—low-potential priority film formation, SEI film composition optimization, and interfacial impedance reduction—it achieves a comprehensive enhancement in the cell's low-temperature performance, rate capability, and high-temperature storage stability. It is particularly suitable for lithium-ion battery systems demanding wide temperature ranges and high-power scenarios (such as power vehicles and energy storage equipment). It provides a new optimization concept of "low film-formation potential + high ion-conduction film" for electrolyte additive development.

Cell Type: 2.5Ah pouch cell Chemistry System: LFP / Artificial Graphite Voltage Window: 2.5 V – 3.65 V Electrolyte Baseline (Common Components): EC : EMC = 3 : 7 , 1 M LiPF6, with LiFSI + VC additives Scheme A: Common Components + 0.5% MMDS Scheme B: Common Components + 0.5% ARC-S35

01 Lower Film-Formation Potential: The film-formation reaction potential of ARC-S35 is 1.8V, which is lower than the 2.0V of MMDS. It preferentially forms a stable SEI film at the graphite-electrolyte interface, preventing the excessive decomposition of the electrolyte at high potentials. 02 EIS Test: ARC-S35 exhibits a lower charge transfer impedance, which facilitates the passage of lithium ions through the SEI film, accelerates lithium-ion migration, and enhances the rate capability of the cell. 03 Initial Coulombic Efficiency (ICE) and Initial Discharge Capacity: The impact on the cell's ICE (90.9% vs. 91.2%) and initial discharge capacity (2.553 Ah vs. 2.554 Ah) is minimal. Its introduction does not significantly increase irreversible capacity loss, showing excellent compatibility.

01 High- and Low-Temperature Discharge Performance: Within the temperature range of -20°C to 55°C, the capacity retention rate of the ARC-S35 group is about 1% higher than that of the MMDS group (e.g., 16.97% vs. 15.91% at -20°C). This further verifies that ARC-S35 has a lower film-formation impedance, reduces interfacial concentration polarization, and is more favorable for the free migration of lithium ions.

01 Rate Capability: Under charge-discharge conditions of ≤1C, there is little difference between the ARC-S35 group and the MMDS group; under conditions of >1C, ARC-S35 outperforms MMDS, with an improvement of over 1% in all cases. 02 Pulse Charge-Discharge Test: The charging and discharging direct current resistance (DCR) are reduced by 4.2% and 4.7% respectively, indicating lower interfacial impedance and smaller resistance to ion migration, which benefits rate charge-discharge performance and suits high-power battery applications.

01 Significant High-Temperature Storage Advantages: After high-temperature storage (60°C & 14d), both capacity retention and recovery rates increase by over 1%, and the internal resistance growth rate decreases by 3.45% (15.11% vs. 18.56%), indicating that the SEI film is more stable at extreme temperatures and suppresses interfacial side reactions. 02 Long-Term Cycling: Capacity retention rate shows no degradation during long-term cycling.

In summary, as a new generation of electrolyte additive, ARC-S35 demonstrates the potential to completely outperform MMDS across all performance metrics, thanks to its significant advantages in film formation, impedance, wide-temperature performance, high-temperature storage, and high-rate capability. Its technological value is reflected not only in performance enhancements but also in providing new insights for electrolyte formulation optimization. ARC-S35 holds broad application prospects in the fields of power and energy storage.