A Supertough and Highly‐Conductive Nano‐Dipole Doped Composite Polymer Electrolyte with Hybrid Li⁺‐Solvation Microenvironment for Lithium Metal Batteries

Abstract Achieving solid polymer electrolytes with ceramic‐like fast single‐ion conduction behavior, separator‐required mechanical properties, and good lithium‐dendrite suppression capability is essential but extremely challenging for the practical success of solid‐state lithium‐metal batteries. The key to overcome this long‐standing bottleneck is to rationally design the Li⁺‐transport microenvironment inside the polymeric ion‐conductors. Herein, the concept of a nano‐dipole doped composite polymer electrolyte (NDCPE) is proposed using surface‐charged halloysite nanotubes (d‐HNTs) as the dopant to achieve a Li⁺‐transport‐friendly microenvironment in poly(vinylidene fluoride) (PVDF) based quasi‐solid electrolytes. Results show that the d‐HNTs doping can immobilize the anions and help dissociate the lithium salt, which leads to an advanced dynamic Li⁺‐interface yielding both a high Li⁺‐transference number (0.75 ± 0.04) and ionic conductivity (0.29 ± 0.04 mS cm⁻¹ @R.T.). Moreover, compared with the commercial separator, the NDCPE thin‐film shows similar toughness, mechanical strength, and puncture resistance, but much superior capability for stabilizing the lithium‐metal anode. To understand the possible doping mechanism, a hybrid Li⁺‐solvation model combining the surface charges of the nanofiller, absorbed solvent molecules, and absorbed polymer chain unit is proposed and discussed for guiding the future studies on advanced hybrid solid polymer electrolytes.