Fast ion-conduction in solid-state Li-S batteries realized by an interfacial-bridge strategy

Polymer-in-salt electrolytes (PISEs) are promising candidates for solid-state lithium-sulfur batteries (SSLSBs) because of their superior ion conductivity to conventional polymer electrolytes. However, their practical application in SSLSBs is hindered by the fast migration of Li ions in PISEs and at the interface between the electrodes and PISEs. Herein, we introduced interfacial bridges in a PAN-based PISE via the in situ polymerization of DOL to address this issue. The interfacial bridges in the PISE enabled Li-ion migration between uncontacted ion clusters, resulting in the PIS-PDOL exhibiting high ionic conductivity (6.9 × 10⁻⁴ S cm⁻¹ at 25 °C) and an improved Li-ion transference number (t_Li⁺ = 0.66). Moreover, the interfacial bridges enabled the fast conduction of Li ions at the electrode-electrolyte interface. Accordingly, the SSLSB with this electrolyte exhibited a discharge capacity of 734 mA h g⁻¹ after 120 cycles at 0.1C and 25 °C and retained good cycling stability at a high current density. This strategy can effectively improve ion conduction between various complex interfaces and can be extended to other solid-state battery systems.