LFP-based binder-free electrodes produced via fused filament fabrication

Abstract

Carbon coated-LiFePO4(LFP) is a strong candidate for lithium-ion battery
(LIB) cathodes due to the combination of safe operation, stable electrochemical performances and positive environmental impact as does not depend on Co, which is toxic and a critical raw material. In this work, we report the development of binder-free LFP cathodes fabricated by Fused Filament
Fabrication (FFF) technology. Several novel Carbon-LFP filaments have been developed to 3D-print LiB cathodes, analysing both the carbon to LFP ratio in the formulation and also the impact of the carbon source used as current collector, i.e., glassy carbon microspheres or carbon black, in the electrochemical performance. LFP remained stable upon debinding and sintering at temperatures as low as 500 °C as determined by XRD. The conductivity of 3D printed LFP monoliths was 2.06x10-4 S∙cm-1 at 50 °C, which is fairly close to that of LFP produced via conventional processing. This is mainly attributed to the preservation of the carbon coating around the LFP particles after debinding and sintering under controlled Ar atmospheres. The LFP-based electrodes containing carbon black or glassy carbon microspheres as conductive additives exhibited specific capacities of 150 mAh∙g-1, and over 95% coulombic efficiency after 100 cycles, showing no significant performance losses. These results largely exceed the performances reported for previous LFP-based electrodes produced via FFF as the non-active binder is removed upon fabrication.

Materials for 3D Printed Metal and Metal‐Ion Batteries

“…This performance is due to the substitution of the binder with the thermoplastic which also allows a solvent-free deposition. [22,23] FDM has also been used to print electrolytes. In this case, the most common strategy is the infiltration of preprinted PLA-based membranes with liquid electrolytes forming quasi-solid electrolytes (QSEs).…”