Mechanically Unwinding Carbon Nanotubes Enables Homogeneous Conductive Networks in High-Loading Dry Cathodes for Lithium-Ion Batteries

초록

The expanding electric vehicle market has driven an urgent demand for high-energy-density lithium-ion batteries (LIBs). Solvent-free dry-processed electrodes offer strong potential for thick electrode development, but increasing thickness exacerbates the difficulty of uniformly dispersing conductive additives, posing a significant challenge for efficient electron and Li-ion transport. Herein, we report mechanically pre-unwound carbon nanotubes (uCNTs) as a morphologically engineered conductive additive with superior dispersibility, enabling continuous and homogeneous conductive networks in high-loading Ni-rich NCM811 cathodes. Ultra-thick dry electrodes (10.5 mAh cm−2, 170 μm) were realized using only 0.5 wt% uCNT—a threefold reduction compared with carbon black—yet delivered 120% higher capacity at 3.0 C and 92.7% capacity retention after 50 cycles. Furthermore, uCNT/natural graphite pouch full-cells (5.0 mAh cm−2, N/P ratio 1.1) demonstrated 89.5% capacity retention with an average Coulombic efficiency of 99.7% after 200 cycles at 0.2 C, validating the practical applicability of uCNT-based dry electrodes. These results show that enhanced CNT dispersibility enables continuous conductive networks that alleviate the long-standing ionic-electronic transport imbalance in thick electrodes. This work provides a practically scalable, solvent-free pre-unwinding strategy that establishes a viable pathway for next-generation high-energy LIBs, coupling superior electrochemical performance with sustainable and industrially relevant manufacturing.

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