Direct-Ink-Writing of All-Solid-State Batteries with Solvent Free, Non-Flammable Electrolytes Toward Wearable Electronics

With the growing potential of the “Internet-of-Everything (IoE),” free-form lithium-ion batteries (LIBs) are emerging as promising candidates for miniaturized electronics due to their high energy density and safety. However, traditional manufacturing methods such as slurry casting and stacking are not well-suited for producing arbitrarily shaped batteries. Three-dimensional (3D) direct ink writing (DIW) has demonstrated significant potential for fabricating intricate 3D structures, enabling a high degree of design flexibility and a low device footprint. To ensure the successful application of DIW in the fabrication of battery components, the inks must possess appropriate rheological properties, including viscosity, surface tension, and adhesion. To date, DIW technology has primarily focused on the fabrication of thick electrodes to enhance areal energy density and power density.
In this presentation, we will introduce a solvent-free, non-flammable, and 3D printable SPE with high ionic conductivity. This solvent-free SPE overcomes the aforementioned challenges faced by traditional SPEs, such as post-annealing process and insufficient ion transport, while also providing thermal stability and eliminating the safety issues encountered with GPEs. Moreover, the SPEs allows the creation of complex structures with outstanding printing resolution of ~100 μm, demonstrating an ionic conductivity of 0.7 mS cm^-1 at room temperature. Compared to a commercial liquid electrolyte and separator, this solid electrolyte is non-flammable and exhibits a low shrinkage or decomposition rate at high temperatures. This polymer solid electrolyte is also well-compatible with LiFePO₄ (LFP) exhibiting good rate capability and cyclability at room temperature. The integration of fully printed current collectors, electrodes, and packaging enables the fabrication of thin-film, fully printed solid-state batteries with enhanced flexibility, making them suitable for free-form applications. Our printable solid polymer electrolyte can pave the way to realize all 3D printed batteries with a high degree of design freedom for next-generation customized personal devices.