Nowadays, rechargeable lithium-ion batteries (LiBs) are among the most widely used energy storage devices due to their potential to provide high quality energy and power density, long-term cycle life, negligible memory effect and low cost. Consequently, LiBs are the preferred energy storage technology for portable electronics, power tools, electrical-based vehicles and reservoir for renewable energy surpluses [1]. On the other hand, several challenges must be overcome before their complete implementation, mainly the stability of high-voltage cathode materials and alternative compositions for electrolytes and anodes to improve current safety issues.
A great deal of research interest is on-going to improve the volumetric and gravimetric energy density via new fabrication procedures. In this context, additive manufacturing technologies (AMs) would play a decisive role to explore new and fully free design alternatives, which constitute a real constraint for current conventional manufacturing processes, within the whole energy range [2].
Fused filament fabrication (FFF) uses ceramic-based polymeric filaments to print electrodes and electrolytes. The possibility to obtain dimensional and chemically compatible inorganic-organic blended compositions in the printed green body and sintered final electrode may boost the use of 3D-printing technologies for battery manufacturing. However, this technology is not mature to produce ceramic electrodes and indeed the number of publications in the FFF field applied to the development of metal-ion batteries is currently rather scarce.
Within this context, we have developed a filament fabrication procedure with up to 72-75 % w of ceramic loading [3]. More specifically, we will show recent results regarding the production via FFF of LiFePO₄ (LFP) and LFP/C-based compositions as LiB cathodes [4]. After 3D printing and further optimization of the debinding process, the resulting electrodes exhibit high chemical and dimensional stability with controlled porosity and thickness of ≈43% and ≈85 mm, respectively.  Using carbon black (CB) as additive conductor to obtain filaments with 65% LFP, 5% CB and 30% polymer, the 3D-printed and further sintered electrodes yield up to 152 and 139 mAh/g at C/2 and 1C, respectively. Similarly, for filaments with 50% LFP, 20% glassy carbon (GC) and 30% organic, electrodes exhibit up to 150 and 130 mAh/g at C/2 and 1C, respectively. Although the electrochemical behaviour is quite similar, extended cycling for moderate current highlights better performances in the case of carbon black-based electrodes.
 
[1] G. Zubi, R. Dufo-López, M. Carvalho, G. Pasaoglu, Renewable and Sustainable Energy Reviews, 89, (2018), 292–308; N. Nitta, F. Wu, J. T. Lee, G. Yushin, Materials Today, 18, (2015), 252–264
[2] J. P. Thomas, M. A. Qidwai, JOM, 57 (3), (2005), 18–24; S. Ekstedt, M. Wysocki, L. E. Asp, Plastics, Rubber and Composites, 39 (3–5), (2010), 148–150
[3] J. Canales-Vázquez, G. B. Sánchez Bravo, J. R. Marín-Rueda, V. Yagüe-Alcaraz, J. J. López-López, ES2640930B1/WO2017191340A1, (2017)
[4] J. M. Ramos-Fajardo, J. F. Valera-Jiménez, I. M. Peláez-Tirado, J. C. Pérez-Flores, M. Castro-García, J. Canales-Vázquez (under review).