Improving conductivity and flexibility of LiFePO4 electrodes via functionalized MWCNT frameworks

Abstract

The demand for flexible, high-performance batteries, free-standing LFP electrodes is being developed without binders or metal collectors. However, due to LFP's low conductivity, conductive additives like CNTs are needed to improve charge transport and ion diffusion. In this study, binder-free and free-standing LiFePO4 (LFP) composite electrodes were developed using oxidized multiwalled carbon nanotubes (OCNTs) as a conductive framework, and their electrochemical performance was systematically evaluated. Functionalized MWCNTs introduced hydrophilic surface groups, enabling uniform dispersion throughout the electrode and forming a conductive network that effectively encapsulates LFP particles. Composite electrodes with 40%, 60%, and 80% LFP (denoted LFP0.4-OCNT, LFP0.6-OCNT, and LFP0.8-OCNT, respectively) were fabricated to optimize the active material-to-conductive matrix ratio. The LFP0.4-OCNT electrode showed the best performance, with a capacity of 177.5 mAh/g at 1C and strong rate capability up to 5C. Its low charge transfer resistance (28 ω) confirms the OCNT network's role in enhancing electron and ion transport. These findings demonstrate that functionalized MWCNTs significantly enhance LFP electrode performance, supporting a simple and scalable strategy for fabricating flexible electrodes with improved energy density, mechanical flexibility, and electrochemical efficiency for next-generation lithium-ion batteries.