Polymer-based LFP cathode/current collector microfiber-meshes with bi- and interlayered architectures for Li-ion battery

In this study, we report the development of a free-standing fiber-based mesh cathode made of electrospun composite microfibers containing 80 wt% lithium iron phosphate (LFP), as well as conductive microfibers containing carbon nano-fillers acting as the current collector (CC). Neither the electrode nor the current collector undergoes post-fabrication treatment or calcination. Scanning electron microscopy confirmed that the meshes are constructed of well-shaped microfibers and exhibit a high porosity, enabling efficient electrolyte penetration and improved electron and ion-transport channels. Two cathode architectures of the LFP/polymer-based CC meshes were explored: bilayered and interlayered. Both architectures are characterized by a high surface-to-volume ratio. The interlayered structure showed superior electrochemical performance due to enhanced LFP-CC fiber-to-fiber contacts and reduced resistance. Comparative analysis with electrospun LFP on aluminum foil revealed comparable specific capacity but higher polarization in the electrospun LFP/CC meshes, attributed to increased internal resistance and limited fiber-to-fiber contacts. However, the electrospun interlayered LFP/CC mesh exhibited significantly higher gravimetric energy density (197 Wh/kg (LFP + CC) and 94 Wh/kg (LFP + Al), respectively), offering lightweight and higher-energy-density electrode materials, thus guiding the design of high-performance flexible lithium-ion batteries.