Porous polymer in polymer structure created using carbon dots for high-performance gel polymer electrolytes

Abstract

A new polymer in polymer structure was constructed, incorporating two distinct polymers: the rigid PVDF–HFP as the porous framework and the flexible PEO, which served both as the filler and the liquid electrolyte absorber. For the first time, the polymeric porous structure was engineered using CDs, which could be recycled through washing and reused in subsequent pore creation processes. The high porosity and robust structure of the PVDF–HFP framework ensured effective deposition of PEO and absorption of the electrolyte. The resulting gel polymer electrolytes (GPEs) exhibited excellent conductivity, a wide electrochemical stability window, and considerable lithium-ion transference numbers at room temperature. These GPEs were employed in lithium metal batteries (LMBs), which exhibited exceptional cycling stability exceeding 3000 h, high rate capability, and a coulombic efficiency of nearly 100%. Both SEM and XPS investigations of lithium anodes dismantled from LMBs after extended cycling revealed the formation of stable solid-electrolyte interphase (SEI) layers on the lithium surface, which effectively hindered dendrite growth and minimized anode corrosion. This research offers a solution for fabricating high-performance GPEs for LMBs with long cycle lifespans while also introducing a new technique for preparing porous polymer materials using CDs.