Amphiphilic Polymer Electrolyte Blocking Lattice Oxygen Evolution from High‐Voltage Nickel‐rich Cathodes for Ultra‐Thermal Stabile Batteries
Jialiang Chen, Yan Lin, Qiang Li, Hao Ren, Linchen Zhang, Yuanyuan Sun, Siyu Zhang, Xinchao Shang, Weidong Zhou, Mingbo Wu, Zhongtao Li, Zhongtao Li
Abstract
Abstract Ni‐rich cathodes have been intensively adopted in Li‐ion batteries to pursuit high energy density, which still suffering irreversible degradation at high voltage. Some unstable lattice O 2− species in Ni‐rich cathodes would be oxidized to singlet oxygen 1 O 2 and released at high volt, which lead to irreversible phase transfer from the layered rhombohedral (R) phase to a spinel‐like (S) phase. To overcome the issue, the amphiphilic copolymers (UMA‐F x ) electrolyte were prepared by linking hydrophobic C−F side chains with hydrophilic subunits, which could self‐assemble on Ni‐rich cathode surface and convert to stable cathode–electrolyte interphase layer. Thereafter, the oxygen releasing of polymer coated cathode was obviously depressed and substituted by the Co oxidation (Co 3+ →Co 4+ ) at high volt (>4.2 V), which could suppressed irreversible phase transfer and improve cycling stability. Moreover, the amphiphilic polymer electrolyte was also stable with Li anode and had high ion conductivity. Therefore, the NCM811//UMA‐F 6 //Li pouch cell exhibited outstanding energy density (362.97 Wh/kg) and durability (cycled 200 times at 4.7 V), which could be stalely cycled even at 120°C without short circuits or explosions.