A Conductive-Robust Ternary Binder for High-loading LiFePO4 Cathodes

Abstract

High-loading LiFePO4 (LFP) cathodes with low binder content are critical for improving cell-level energy density while retaining long cycle life and safety. However, the intrinsically low electronic conductivity of LFP, together with transport limitations and stress accumulation in high-loading electrodes, imposes stringent requirements on binder systems. Herein, we report a ternary functional binder composed of poly(3,4-ethylenedioxythiophene) (PEDOT), carboxymethyl cellulose (CMC), and single-walled carbon nanotubes (CNTs), denoted as the PCC binder, designed via synergistic electronic-mechanical coupling. PEDOT provides continuous electronic pathways, CMC regulates polymer dynamics through dynamic supramolecular coupling, and CNTs form a conductive-mechanical framework enabling cooperative load bearing. As a result, the resulted LFP electrodes exhibit reduced resistance, suppressed polarization, and improved cycling stability, compared with a conventional aqueous binder LA133. Notably, the LFP cathodes with a high areal loading of ~22 mg cm-2 corresponding to a loading well beyond typical laboratory-scale electrodes-retain 73.4% of their capacity after 2800 cycles. This work demonstrates a viable binder design strategy for low-binder, high-loading LFP cathodes.