Conflicting entropy-driven zwitterionic dry polymer electrolytes for scalable high-energy all-solid-state batteries

Abstract

Inorganic electrolytes dominate all-solid-state batteries (ASSBs), but face critical limitations, including interfacial instability, complex manufacturing, and challenges in operating under commercially viable conditions. Here, we present a transformative approach using zwitterionic dry polymer electrolytes (ZPEs) designed via a conflicting entropy strategy to enable scalable energy-dense ASSBs. Guided by Flory-Huggins theory, liquid-state zwitterionic monomers exhibit higher mixing entropy with Li salts compared to conventional long-chain polymers, forming homogeneous monomer/salt mixtures with enhanced intermolecular electrostatic interactions to promote salt dissociation. In situ polymerization of these mixtures yields directionally aligned ion channels decoupled from the polymer backbone, characterized by reduced conformational entropy, allowing rapid Li+ migration via an ion-hopping mechanism under ambient conditions. The ZPEs are seamlessly incorporated as a solid catholyte into pre-fabricated high-areal-capacity (10.0 mAh cm(-)(2)) LiNi0.8Co0.1Mn0.1O2 positive electrodes, ensuring compatibility with existing cell manufacturing processes and has the potential to reduce production complexity and cost. Paired with thin Li-metal negative electrodes (N/P (negative-to-positive electrode capacity) ratio = 1.0), pouch-type ASSB full cells demonstrate a specific energy and energy density of 516 Wh kg-1 and 1329 Wh L-1 (excluding the pouch packaging) and stable cycle life at practical operating conditions (25 degrees C and 0.5 MPa) in such a constrained cell configuration.