Elastic Interfacial Layer Enabled the High‐Temperature Performance of Lithium‐Ion Batteries via Utilization of Synthetic Fluorosulfate Additive

Abstract The key to producing high‐energy Li‐ion cells is ensuring the interfacial stability of Si‐containing anodes and Ni‐rich cathodes. Herein, 4‐(allyloxy)phenyl fluorosulfate (APFS), a multi‐functional electrolyte additive that forms a mechanical strain‐adaptive solid electrolyte interphase (SEI) comprising LiF and polymeric species, and a thermally stable cathode–electrolyte interface containing SO and SF species. The radical copolymerization of vinylene carbonate (VC) with APFS via electrochemical initiation creates a spatially deformable polymeric SEI on the SiG‐C (30 wt.% graphite + 70 wt.% SiC composite) anode, with large volume changes during cycling. Moreover, the APFS‐promoted interfacial layers reduce Ni dissolution and deposition. Furthermore, APFS deactivates the Lewis acid PF 5 , thereby inhibiting hydrolyses that produce unwanted HF. These results indicate that the combined use of VC with APFS allows capacity retentions of 72.5% with a high capacity of 143.5 mAh g −1 in SiG‐C/LiNi 0.8 Co 0.1 Mn 0.1 O 2 full cells after 300 cycles at 45 °C.