Innovative Additive Manufacturing of LiNi_xMn_yCo_zO₂ as Positive Electrode Material for Lithium-Ion Batteries Through the Precursor Approach

While current commercial lithium-ion batteries consist of two-dimensional (2D) planar designs with specific geometries (pouch cell, prismatic, cylindrical, coin cell...) consisting of stacked sheets of electrodes, separator and current collectors [1], innovative approaches are now required to enable the development of 3D complex architectures. These architectures have been reported to significantly improve the electrochemical performances in term of power and capacity [2]. The request to build flexible, wearable and customizable batteries of any shape while maximizing the energy storage, as well as diminishing volume and weight, can be addressed by merging the current lithium-ion batteries investigations with cutting-edge additive manufacturing technologies, colloquially known as 3D-printing [3-5].<br/><br/>This work deals with the utilization of the vat photopolymerization technique to produce high-resolution three-dimensional electrodes made of LiNi_xMn_yCo_zO₂ (NMC) from a bespoke UV-photopolymerizable composite resin through an unconventional precursor approach. Classical resins used to perform vat photopolymerization of ceramic and metal objects presents the disadvantage of containing solid particles that increase the viscosity of the resin, consequently rendering the printing difficult. This work targets an alternative approach that consists in adding soluble precursors salts that can be oxides, nitrates, or sulfates to the photopolymerizable base resin. The only requirement for the precursor salts is to be soluble in the base resin that can be ethanol-based or water-based. The advantage of this approach is that the resin does not increases drastically its viscosity associated with the introduction of solid charges, and that the precursor salts are mixed at the molecular level thanks to their solubility in the resin, thus avoiding UV light-scattering during 3D printing. In this approach, the formation of the solid material takes place in-situ during the thermal post-processing steps.<br/><br/>The elaboration and characterization of the printable UV-photopolymerizable composite resin containing stoichiometric amounts of soluble precursor salts, monomer and photoinitiator will be discussed in this talk. The 3D printing of complex electrode structures that otherwise would not be possible with classical battery production methods will be shown. The crucial debinding and sintering steps needed to obtain the pure NMC material will be discussed as well, accompanied by XRD data proving the crystallinity of the material. As anticipated by the good crystallinity, electrochemical characterization exhibiting the good performance of the NMC materials in half-cell will also be presented. This work aims to show early results of 3D printing of battery components via vat photopolymerization technique, in view to assess its capability to print complex shape-conformable functional components.<br/>References<br/>[1] N. Nitta, F.X. Wu, J.T. Lee, G. Yushin, Li-ion battery materials: present and future, Materials Today 18(5) (2015) 252-264.<br/>[2] J.W. Long, B. Dunn, D.R. Rolison, H.S. White, Three-dimensional battery architectures, Chemical Reviews 104(10) (2004) 4463-4492.<br/>[3] A. Maurel, S. Grugeon, B. Fleutot, M. Courty, K. Prashantha, H. Tortajada, M. Armand, S. Panier, L. Dupont, Three-Dimensional Printing of a LiFePO4/Graphite Battery Cell via Fused Deposition Modeling, Scientific Reports 9 (2019).<br/>[4] D.W. Yee, M.A. Citrin, Z.W. Taylor, M.A. Saccone, V.L. Tovmasyan, J.R. Greer, Hydrogel-Based Additive Manufacturing of Lithium Cobalt Oxide, Advanced Materials Technologies 6(2) (2021).<br/>[5] A. Maurel, A. C. Martinez, S. Grugeon, S. Panier, L. Dupont, P. Cortes, C. G. Sherrard, I. Small, S. T. Sreenivasan, E. Macdonald, Toward High Resolution 3D Printing of Shape-Conformable Batteries via Vat Photopolymerization: Review and Perspective, IEEE Access 9 (2021).