3D Printing of Ridged FeS₂ Cathodes for Improved Rate Capability and Custom-Form Lithium Batteries

Abstract

Additive manufacturing can enable the fabrication of batteries in nonconventional form factors, enabling higher practical energy density due to improved material packing efficiency of power sources in devices. Furthermore, energy density can be improved by transitioning from conventional Li-ion battery materials to lithium metal anodes and conversion cathodes. Iron disulfide (FeS 2 ) is a prominent conversion cathode of commercial interest; however, the direct-ink-write (DIW) printing of FeS 2 inks for custom-form battery applications has yet to be demonstrated or optimized. In this work, DIW printing of FeS 2 inks is used to systematically investigate the impact of ink solid concentration on rheology, film shape retention on arbitrary surfaces, cathode morphology, and electrochemical cell performance. We find that cathodes with a ridged interface, produced from the filamentary extrusion of highly concentrated FeS 2 inks (60−70% solids w/w%), exhibit optimal power, uniformity, and stability when cycled at higher rates (in excess of C/10). Meanwhile, cells with custom-form, wave-shaped electrodes (printed FeS 2 cathodes and pressed lithium anodes) are demonstrated and shown to exhibit similar performance to comparable cells in planar configurations, demonstrating the feasibility of printing onto complex geometries. Overall, the DIW printing of FeS 2 inks is shown to be a viable path toward the making of custom-form conversion lithium batteries. More broadly, ridging is found to optimize rate capability, a finding that may have a broad impact beyond FeS 2 and syringe extrusion.

3D printing of hierarchically micro/nanostructured electrodes for high-performance rechargeable batteries

“…According to the previous literature, printable inks play important roles in the DIW printing process. [53][54][55] Ideally, the printable ink can stay as a solid under low working pressures and flow as a fluid under high working pressures. However, the inks with both too low and too high viscosity can be detrimental to the DIW printing process, as they fail to maintain their solid shape or clog the nozzle.…”

“…Furthermore, Cardenas et al utilized FeS 2 ink to print 3D ridged FeS 2 electrodes through DIW printing. 53 The concentration of the ink could affect the rheology, film geometry, cathode morphology, and electrochemical performance. The inks with 60–70 wt% solid concentration could form stable electrodes through DIW printing.…”

Fast-Charging, Binder-Free Lithium Battery Cathodes Enabled via Multidimensional Conductive Networks

“…One commonly adopted strategy is to produce anisotropic electrode architectures through new fabrication techniques that reduce pore tortuosity, such as magnetic templating, ice templating, , or 3D printing. , These techniques are used to create vertically aligned pathways for ion transport and have shown lab-scale success, especially for high-areal-loading battery electrodes; however, they often involve complex processing or specialized equipment setups. A possible way to control electrode morphology without introducing these complexities is through the tuning of filler materials .…”