Many scientists are looking at innovative 3D designs to enhance the performance of LIB (Li-ion battery ) due to the increased demand for portable energy devices coupled with the rise of the LIB. Additionally, it is essential to develop batteries with volumetric energy and power density. Among the currently known techniques for creating 3D batteries, fused deposition modeling (FDM) has proven to be very promising due to low manufacturing cost, design flexibility, and ease of use. The goal of this Master’s thesis was to create a positive electrode filament for the FDM process. The filament was composed of LiFePO4 (LFP) as the Li+ source, carbon nanofiber (CNF), multiwalled carbon nanotube (MWCNT), or carbon black (C45) for the electronic percolation network. At the same time, polymer A was used to host the charges (LFP and carbon) and polymer B to form the porous network. Additionally, polypropylene (PP) was chosen as polymer A, while polycaprolactone (PCL) or polyethylene oxide (PEO) was used as PB. Moreover, to produce 3D printable filaments and subsequently printed disks, several fabrication methods such as the solvent, solvent plus sonication, master batch, and powder batch methods were implemented. Characterization techniques including scanning electron microscope (SEM), galvanostatic charge and discharge, contact angle, and rheometric measurements were performed to determine the best ratio and formulation to produce a 3D printed positive electrode. The SEM micrographs obtained confirmed the wetting coefficient and viscosity predictions regarding the location of LFP (at the interface between PP and PCL or PEO), while CNF was determined to be mainly in PP with some at the interface and few in PEO or PCL. Moreover, the master batch method allowed the LFP quantity to be increased from 49 to 73 wt%, while the samples fabricated using the solvent method had higher capacity retention. Finally, sample D-PCL Study which is composed of 33 wt% PP/ 13 wt% PCL/ 49 wt% LFP/ 5wt% CNF, possessed the highest capacity retention at the end of the discharge cycle at C/40 even when compared to a powder LFP-based electrode (90 wt% LFP/ 10 wt% C45) (157.4 vs. 145.5 mAh/g at C/40). Also, a combination of 50 wt% CNF and 50 wt% MWCNT is promising since it lowered the electrode structural collapse during cycling. In conclusion, these results pave the way towards developing high-performance FDM 3D printable electrode filaments and 3D printing of shape-conformable LIB for applications including but not limited to portable, microelectronics, and aerospace.
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