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: poly(styrenesulfonate) (PEDOT:PSS), carboxymethyl cellulose (CMC), and single-walled carbon nanotubes (CNTs), denoted as the PCC binder, designed via synergistic electronic–mechanical coupling. PEDOT:PSS 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.