From Inert Spacer to Functional Conductor: A Paradigm Shift in Grinding Aids Enables Dual-Channel Conductive Networks for High-Performance LiFePO ₄ Cathodes

Conventional conductive agents for lithium-ion batteries often face a critical trade-off among dispersion uniformity, electronic conductivity, and interfacial ion kinetics. Although ball-milling additives like metals or oxides are commonly used to disperse carbon nanotubes (CNTs), they typically act as inert spacers that do not contribute to─and often hinder─electrical percolation. Herein, we introduce a functionalization strategy through wet ball milling to construct hybrid conductive agents with CNTs. Although zirconium phosphate (ZrP) effectively exfoliates CNT bundles via its lamellar structure, its inherent insulation leads to severe electron-blocking barriers, resulting in rapid capacity decay (13% retention after 200 cycles at 0.5 C). In stark contrast, replacing ZrP with metallic titanium carbide (TiC) yields TiC/CNT hybrids that not only suppress CNT reaggregation through geometric confinement but also engineer a multifunctional interface that establishes integrated electron-ion dual channels. The resulting LiFePO₄ cathode exhibits exceptional cyclability with 96.7% capacity retention after 200 cycles at 0.5 C, remarkable rate performance delivering 47% capacity at 10 C. More importantly, electrochemical impedance spectroscopy revealed the exceptional durability of the TiC/CNT conductive network, which exhibited a minimal resistance growth of only 11.75% over 200 cycles─an order of magnitude lower than the 88.3% increase observed with conventional acetylene black. These improvements are attributed to TiC's unique surface chemistry and interfacial properties: high electronic conductivity eliminates interfacial barriers, two-dimensional confinement aligns CNTs for efficient electron transport, and its lithiophilic surfaces facilitate Li⁺ desolvation kinetics, thereby enhancing ion transport across the electrode-electrolyte interface. This work represents a paradigm shift from inert dispersants to functional interface-engineered conductive aids, underscoring the synergy of dual-channel transport and providing a scalable pathway toward high-rate lithium-ion batteries.