Triple-anchoring binder for improved cyclability of dry-processed NCM811 cathodes in lithium-ion batteries

Dry-processed electrodes are promising due to solvent-free and low-cost features, but they are struggling with not only the limited mechanical properties of the binder, but also the intrinsic degradation of active materials. To simultaneously reinforce the binder and stabilize the crystal structure of LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) in a dry-processed cathode, a dynamic triple-drawing strategy is employed to design a triple‑anchoring binder. A soft hyperbranched chain is introduced to achieve segmental drawing, crosslinking the crystalline domains of polytetrafluoroethylene and enhancing binder toughness. Lone-pair electrons on the binder functional groups create lattice-ion drawing by coordinating with the empty orbitals of surface transition-metal ions and drawing them away from cation mixing to achieve a more stable NCM811 lattice structure. The same Lewis-base sites also accomplish free-ion drawing, capturing the free transition-metal ions generated by HF corrosion and blocking their dissolution. Consequently, the fracture energy of the binder increases by 62.24%, allowing it to better accommodate the mechanical strain and maintain electrode integrity. Dry-processed NCM811 cathodes fabricated with this binder retain 95.77% of their initial capacity after 100 cycles at 0.2 C and 80.19% after 450 cycles at 1 C. These results provide a scalable route to high-performance, long-life, solvent-free electrodes for lithium-ion battery production.