Precise regulation of hydrogen bond networks for rapid ion transport in PEO-based composite solid electrolytes

Abstract

PEO-based composite solid electrolytes (CSEs) hold significant promise for high-energy all-solid-state lithium metal batteries (SSLMBs) due to their excellent processability and enhanced safety. However, the unregulated chemical environment at the organic–inorganic interface could induce the agglomeration of inorganic fillers and hinder interfacial ion transport, thereby deteriorating the overall electrochemical performance of the CSEs. To address these challenges, we pioneered a controllable hydrogen-bonded interfacial layer by incorporating [3-(2-aminoethylamino)-propyl]trimethoxysilane (AEAPTMS)-modified LLZO nanofibers (A@LLZO) into the PEO matrix. By precisely optimizing the mass ratio of AEAPTMS-to-LLZO, the hydrogen bonds between the amino/imino groups in A@LLZO and the ether oxygen groups in PEO can effectively enhance the mobility of PEO chains and modulate the local Li⁺ coordination environment, thereby facilitating the formation of continuous and low-energy-barrier Li⁺ transport pathways. As a result, CSEs achieve a high ionic conductivity of 0.59 mS cm⁻¹ and a Li⁺ transference number of 0.63. The assembled Li‖LiFePO₄ (LFP) full cell can deliver a stable capacity of 114 mA h g⁻¹ under 0.5C over 150 cycles at 60 °C. This work highlights the significant potential of precisely regulating hydrogen bond interactions at the organic–inorganic interface to enhance the performance of CSEs, offering valuable guidance for the development of high-performance SSLMBs.