"Gene-Editing" Design Upgrades Eutectic-Polymer Electrolytes with Ultra-High Li+ Conductivity.

Abstract

Deep eutectic polymer electrolytes (DEPEs) have emerged as highly promising next-generation electrolytes, offering unparalleled electrochemical performance and safety. Their excellence stems from a synergistic blend of the robust mechanical stability of solid polymer electrolytes and the exceptional interfacial wettability and superior thermal resilience of deep eutectic electrolytes. However, conventional DEPEs frequently exhibit suboptimal Li⁺ conductivity due to strong coordination between Li⁺ and oxygen-containing polymer moieties. Inspired by the concept of 'gene-editing' in biology, we propose a novel deep eutectic polymer electrolyte (GEPE) with precisely tailored molecular architectures This approach exploits the steric hindrance and electron-withdrawing inductive effects from isophorone diisocyanate-derived segments to reduce Li⁺-polymer interactions, thereby enabling an extraordinary ionic conductivity of 3.00 mS cm⁻¹ at 25 °C and a Li⁺ transference number of 0.61. Remarkably, GEPE exhibits extraordinary cycling stability in Li||Li symmetric cells for over 3000 h, demonstrating dendrite-free Li metal deposition during prolonged cycling. Moreover, the assembled lithium metal batteries demonstrate exceptional electrochemical performance when incorporating diverse cathodes, including LiNi_0.5Co_0.2Mn_0.3O₂, LiNi_0.8Co_0.1Mn_0.1O₂, and LiFePO₄. Notably, the Li|GEPE|LiFePO₄ cells achieve an impressive nearly 100% Coulombic efficiency and remarkable long-term stability over 10 000 cycles at 5C.