Morphology-Driven Conductive Network Design for Low-Tortuosity Solvent-Free Thick LiFePO₄ Electrodes

Solvent-free electrode processing has attracted growing attention as a scalable and sustainable approach for fabricating high-energy-density lithium-ion batteries. However, thick electrodes often suffer from sluggish ion transport, high tortuosity, and severe polarization, which limit their electrochemical performance. In this study, we investigated how the morphology of conductive agents affects the microstructure and charge-transport behavior of solvent-free LiFePO₄ thick electrodes. Three types of conductive additives, including 0D Super P, 1D multi-walled carbon nanotubes, and 2D graphene nanoplatelets, were incorporated into PTFE-based LiFePO₄ electrodes with a thickness of 250 μm. Among them, the multi-walled carbon nanotube electrode exhibited a highly interconnected fibrous network, leading to improved pore connectivity, high porosity, and reduced tortuosity. As a result, the optimized electrode delivered enhanced lithium-ion transport, lower polarization, high specific and areal capacities, and stable cycling performance. These results demonstrate that conductive agent morphology is a critical design parameter for controlling tortuosity in dry-processed thick electrodes and provide practical guidance for developing high-loading lithium-ion battery electrodes.