Defect-rich Carbon Induced Built-in Interfacial Electric Field Accelerating Ion-conduction towards Superior-stable Solid-state Batteries

Abstract

The electrochemical performances of composite solid-state electrolytes (CSEs) cannot satisfy the application requirements of solid-state batteries (SSBs) due to the low concentration of movable cations with disordered and slow cation transportation. Herein, a designed CSE with a built-in interfacial electric field (D-CSE) is successfully constructed via defect engineering of electron-conducting carbon. The electrons would transfer and construct a built-in interfacial electric field (IEF) at the phase interface due to the different Fermi energy levels of the defect-rich carbon and polymer matrix. The built-in IEF would promote the dissociation of alkali-metal salts to release free cations, and provide an extra driving force to boost the transportation of cation. Additionally, the defect-rich carbon could regulate the distribution of electric field to enable rapid cation transfer. In terms of sodium, these coupling effects contribute to the high ionic conductivity (0.67 mS cm−1) and transference number (0.77) of D-CSE. Consequently, D-CSE-based solid-state sodium metal batteries exhibit remarkable cycling stability (0 °C, 80.9%, 500 cycles; 80 °C, 80.1%, 2500 cycles). This strategy of built-in IEF broadens the perspective achieving a uniform and rapid ion transportation and paves the way for achieving superior-stable SSBs.