Enhancing interfacial Li+ transport and dielectric properties in poly(ethylene oxide)-based all-solid electrolytes via inactive g-C3N4 nanosheets filler incorporation

Li, Z. and Zhang, W. and Chen, Y. and Lin, Q. and Zhang, L. and Tao, J. and Kolosov, O.V. and Li, J. and Lin, Y. and Huang, Z. (2024) Enhancing interfacial Li+ transport and dielectric properties in poly(ethylene oxide)-based all-solid electrolytes via inactive g-C3N4 nanosheets filler incorporation. Journal of Materials Science and Technology, 183. pp. 184-192. ISSN 1005-0302

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Abstract

The advancement of all-solid-state Li metal batteries (ASSLMBs) faces a major challenge in the growth of lithium dendrites on the anode-electrolyte interface. In this study, we propose a dual-filler approach using poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) that combine Li1.4Al0.4Ti1.6(PO4)3 (LATP) ion-conductive particles with graphitic carbon nitride (g-C3N4) nanosheets. Analysis through second harmonic resonance enhanced electrostatic force microscopy and critical current density (CCD) tests reveal that the g-C3N4 additives form nano-capacitors at the SPE-lithium interface, effectively reducing sudden changes in current densities. The distribution of relaxation time constant (DRT) measurements confirms that the g-C3N4 filler suppresses uncontrolled Li dendrite growth, effectively mitigating battery aging caused by anode interfacial degradation. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis indicates that the nitrogen-containing organic groups in g-C3N4 are reduced to form a stable interfacial layer with lithium metal. As a result of these enhancements, the electrolyte demonstrates remarkable interfacial stability in Li/Li symmetrical cells at 0.65 mA/cm2 and delivers promising performance in assembled Li-LiFePO4 batteries, achieving a reversible capacity of 121.6 mAh/g at 1 C after 200 cycles. These findings highlight the potential of dual-filler PEO-based SPEs for promoting interfacial lithium-ion transport in all-solid-state Li metal batteries.