(Invited) Opening Twisted Molecular Chains of High Solid Content Screen Printable Ink for Screen-Printed Low-Tortuosity Electrodes

Abstract

Reducing the tortuosity of electrodes is an efficient technique for enhancing the charge transfer inside electrodes and boosting the fast-charging capabilities of lithium-ion batteries for electric vehicles. Compared to reported complex methods, screen printing is facile, economical, and printing pattern controllable. More importantly, the roll-to-roll screen printing equipment can be integrated into the existing electrode production system, allowing for the industrialization of low-tortuosity electrodes. However, the absence of screen-printable inks with a high solid content restricts the ink transfer volume per printing, lowering production efficiency and raising the price of screen-printed electrodes. By integrating rheological characteristics analysis, X-ray computed tomography characterization, and coarse-grained molecular dynamics (CGMD) simulation, we are able to recognize and illustrate the relevance of the molecular chain state in high-solid-content ink for screen printability. Additionally, we propose and develop a unique preparation procedure for producing high-solid-content screen-printable inks. In addition, the electrochemical performance of screen-printed electrodes was evaluated in order to enclose the importance of electrode micromorphology. This finding lays the door for the industrialization of screen-printable inks with high solid content and encourages additional research into screen-printed architectures with functional electrodes.In this work, we demonstrated for the first time that the molecular chains within high-solid-content inks should be untangled to obtain outstanding screen printability. Specifically, the twisted molecular chains serve as extra networks that drag certain particles within the electrode ink onto the mesh, hence diminishing its screen printability. Therefore, we suggest a two-step approach for opening the twisted molecular chains of inks with a high solid content of 60%. Employing this type of ink, the mass loading per printing layer elevates to about 5 times greater than the existing cathode inks. After opening the twisted chains, the LiNi0.6Mn0.2Co0.2O2 cathode ink exhibited a lower viscosity, a faster thixotropic recovery, and superior screen printability than the ink containing twisted chains. Furthermore, due to the improved internal architectural integrity of screen-printed electrodes printed by the excellent screen-printability of ink, the electrode printed with optimized inks displayed a 33% larger charge capacity at 6C with a mass loading of 6.5 mg/cm2 than that produced with chains-twisted ink. In addition, based on the fundamental of the two-step approach, we present optimization approaches for altering screen-printable inks for a variety of circumstances. This idea could promote the coupling of screen printing with the production of functional electrodes and could be utilized for the production of screen-printable inks for all fields.