Electronic products have become the essential part of our daily life, and Li-ion battery is of particular interest because of their high power and energy density and long cycle life. Noval electronic devices with multiple shapes require configuration designable energy storage which can be integrated seamlessly into their limited space. While 3D printing of rechargeable batteries has received immense interests to advance the next generation of 3D energy storage devices, challenges of 3D printed electrolyte still exist. Additional processes, especially for solvent evaporation, are required for previous studies of electrolyte fabrication, which hinders the simultaneous production of electrode and electrolyte in all 3D printed batteries.
Herein, we developed an elevated-temperature DIW 3D-printing technique, and designed a solid-state electrolyte ink, enabling 3D printing of hybrid solid-state electrolyte batteries. In the proposed elevated-temperature DIW process, the hybrid electrolyte ink is directly printed on electrodes without any surface treatment for the substrate and post-processing for the electrolyte, through which the preparation of electrolyte and its incorporation within a battery will be of higher efficiency and lower cost. The hybrid solid-state electrolyte consists of solid polymer matrices and ionic liquid. The porous solid polymer matrix provides plentiful channels for Li-ion diffusion and improves the mechanical properties of the battery. The ionic liquid maintains its liquid form, preserving its ionic conductivity and electrochemical properties. TiO2 nanoparticles were added into the PVDF-co-HFP based polymer inks to modify their viscosity, tune the contact angles and improve the electrochemical performances. In addition, the hybrid electrolyte printed by the elevated-temperature DIW process shows a lower interfacial resistance due to a unique dense interface formed between the electrolyte and electrode. Interestingly, the interfacial resistance in this method was reduced significantly compared with the traditional method of stacking electrolyte on an electrode.