Liquid Metal Electrode Ink for Printable Lithium Ion Batteries

Recent advancements have significantly improved the flexibility of lithium‐ion batteries (LIBs). The battery electrode contains a reaction layer and a current collector layer. Flexible battery electrodes, in which these layers are integrated, are fabricated in a single process, simplifying the electrode fabrication process. However, to date, integrated electrodes have lower conductivity than conventional two‐layer electrodes, and the process that maintains conductivity has not been simplified. This study proposes a liquid metal electrode ink that simultaneously plays the role of the reaction and current collector layers with high conductivity and can be formed in a single process via printing. It employs a gallium‐based liquid metal as a liquid current collector, embedded with Li 4 Ti 5 O 12 or Li 2 TiS 3 as active materials. These liquid metal electrodes exhibit a high electronic conductivity of 10 4 S cm −1 and can be fabricated without requiring the lengthy postprocessing time associated with conventional inks. Moreover, the ink can be applied directly to various insulating and nonflat curved substrates, demonstrating its charge–discharge performance, even when bent to a 1 mm radius to maintain flexibility. Liquid metal‐based electrode inks simplify the LIB fabrication process, contributing to efficient production methods for electrodes in future LIBs.