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

Area of Science:

• Materials Science
• Electrochemistry
• Additive Manufacturing

Background:

• Additive manufacturing offers nonconventional battery form factors for higher practical energy density.
• Transitioning to lithium metal anodes and conversion cathodes can further enhance energy density.
• Iron disulfide (FeS2) is a promising conversion cathode, but its direct-ink-write (DIW) printing for custom batteries is underexplored.

Purpose of the Study:

• To investigate the impact of ink solid concentration on DIW printing of FeS2 inks.
• To optimize rheology, film shape retention, cathode morphology, and electrochemical performance.
• To demonstrate custom-form factor batteries using DIW printed FeS2 cathodes.

Main Methods:

• Systematic investigation of FeS2 ink solid concentration (60-70% w/w%).
• Direct-ink-write (DIW) printing of FeS2 inks onto various surfaces.
• Rheological analysis, morphological characterization, and electrochemical cycling performance evaluation.

Main Results:

• Highly concentrated FeS2 inks (60-70% solids) produced ridged cathodes with optimal power, uniformity, and stability at higher rates (>C/10).
• Custom-form, wave-shaped electrodes (printed FeS2 cathodes, pressed lithium anodes) demonstrated performance comparable to planar configurations.
• Feasibility of printing onto complex geometries was confirmed, showcasing potential for intricate battery designs.

Conclusions:

• DIW printing of FeS2 inks is a viable method for fabricating custom-form conversion lithium batteries.
• Ridged cathode interfaces, achieved through filamentary extrusion of concentrated inks, significantly enhance rate capability.
• The findings have broader implications for optimizing rate performance in syringe-extruded materials beyond FeS2.