3D Printing of Gel Polymer Electrolytes for Sodium-Ion Batteries

Abstract

In order to maximize the capabilities of existing battery chemistries, a big effort has been recently focused on manufacturing more complex battery structures, which promotes 3D lithium ion diffusion resulting in an increase in power density.1-3 The current limitation is still the manufacturing part, which is often complex and expensive for mainstream production. 3D printing appears in this context as an exceptional tool to fill the gaps for 3D battery manufacturing. Among the 3D printing processes, vat photopolymerization is especially interesting thanks to its high printing resolution through a layer-by-layer curing approach that solidifies a UV-photocurable resin. Multiple examples of functional 3D printed batteries manufactured by various methods have been reported in the literature.4-7 Most of the recent works have been focused on half-cells where only one electrode is printed, or complete cells containing printed electrodes but using a non-printed conventional separator-electrolyte couple in between. Among the alternatives to replace this couple for a functional and printable material, gel polymer electrolytes appear as an appropriate option because they possess the advantages of a liquid electrolyte, without severely compromising the mechanical integrity. In addition, they exhibit competitive ionic conductivity and enhanced safety in comparison to liquid electrolytes, and they do not require a thermal post-processing step to be manufactured. Combining the knowledge in this topic with the design freedom that 3D printing allows will certainly contribute to obtaining the next generation of 3D printed batteries. In a first instance, this work will show a brief overview about suitable UV-photocurable resin compositions that can be employed as gel polymer electrolytes in sodium-ion batteries, with a view to employ them as material feedstock in the high-resolution vat photopolymerization process. The freedom of design that 3D printing allows will be then shown through a variety of printed items that transcend the well-known tape casting method to produce conventional gel polymer electrolytes. Finally, a variety of electrochemical tests to prove stability, ionic conductivity and performance within sodium-ion batteries will be shown. Talin, A. A. et al. Fabrication, Testing, and Simulation of All-Solid-State Three-Dimensional Li-Ion Batteries. ACS Appl. Mater. Interfaces 8, 32385–32391 (2016).Liu, Y. et al. Transforming from planar to three-dimensional lithium with flowable interphase for solid lithium metal batteries. Sci Adv 3, eaao0713 (2017).Long, J. W., Dunn, B., Rolison, D. R. & White, H. S. 3D architectures for batteries and electrodes. Adv. Energy Mater. 10, 2002457 (2020).Cheng, M., Deivanayagam, R. & Shahbazian-Yassar, R. 3D printing of electrochemical energy storage devices: A review of printing techniques and electrode/electrolyte architectures. Batter. supercaps 3, 130–146 (2020).Pang, Y. et al. Additive manufacturing of batteries. Adv. Funct. Mater. 30, 1906244 (2020).Zeng, L. et al. Recent progresses of 3D printing technologies for structural energy storage devices. Materials Today Nano 12, 100094 (2020).Maurel, A. et al. Toward High Resolution 3D Printing of Shape-Conformable Batteries via Vat Photopolymerization: Review and Perspective. IEEE Access 9, 140654–140666 (2021).