Enabling ultra-high-loading LiFePO4 cathodes via a conductive binder architecture with minimized inactive content

초록

Achieving ultra-high active material loading in lithium iron phosphate (LiFePO4, LFP) cathodes is essential for enhancing the performance of LFP-based lithium-ion batteries. However, conventional cathodes typically contain around 20% inactive binders and conductive additives. Here, we present a bifunctional binder composed of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and polyethylene glycol (PEG), reinforced with single-walled carbon nanotubes (SWCNTs) to provide strong adhesion, thermal stability, and high electronic conductivity while minimizing inactive content. By optimizing the PEDOT:PSS/PEG ratio, LFP cathodes with 4 wt% binder reach 96% active material loading, delivering a specific capacity of similar to 160 mAh g(-)& sup1; and excellent rate performance (similar to 106 mAh g(-)& sup1; at 8 C). Incorporating SWCNTs enables further reduction of binder content to 2 wt% while maintaining robust cohesion and high conductivity, resulting in strong rate capability of similar to 131 mAh g(-)& sup1; at 8 C and stable cycling over 1000 cycles. Even electrodes with 99% active material operate reliably on a graphite-coated Al current collector, achieving similar to 132 mAh g(-)& sup1; at 8 C and similar to 3.5 mAh cm(-)& sup2; areal capacity. Furthermore, full-cell evaluations with graphite anodes confirm the practical applicability of this binder system, achieving similar to 125 mAh g(-)& sup1; at 8 C and long-term cycling stability even at 60 degrees C.

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