Dual-fibrous PTFE structure enabling uniform and thick dry electrodes for high-energy-density and long-lasting batteries

Abstract

Dry-processed electrodes based on poly(tetrafluoroethylene) (PTFE) binder have emerged as a promising technology for sustainable, low-cost and high-areal-capacity electrode manufacturing. However, understanding its fibrillation behaviour becomes a key engineering factor to achieve mechanically robust electrodes with high electrochemical performance. Herein, we present a dual-fibrous dry electrode (DDE) fabricated via a multi-step grinding and kneading process. Compared to conventional single-type fibrous structures, the proposed DDE exhibits a more uniform material distribution, enabling better electronic conductivity and reaction homogeneity, which in turn results in better cycling stability. Additionally, the PTFE rope in the DDE demonstrates excellent mechanical integrity and edge uniformity-critical attributes for roll-to-roll manufacturing. Overall, our DDE achieves a high areal capacity of 10.1 mAh cm-2 with stable cycle retention. Furthermore, a 1.2 Ah-class stacked pouch full cell incorporating the DDE delivers a high energy density of 349 Wh kgcell-1/800 Wh Lcell-1 when paired with a lithium metal anode, and exhibits 80.2% capacity retention after 600 cycles when paired with a graphite anode, demonstrating superior performance compared to previously reported dry electrodes.