Design of 3D Printed Batteries with Printable Water-in-Salt Gel Polymer Electrolyte

3D printing, also known as additive manufacturing (AM), has emerged as a promising strategy to design and fabricate future energy storage devices. The benefits of 3D printed batteries include versatile, adaptable shape and geometry, enhanced performance with new architectural design, and the ability to integrate printing power sources with other 3D printable devices. Although significant progress has been reported, current 3D printed batteries design still presents several limitations. The printed battery cells may use a solid electrolyte, which can only be operated at an elevated temperature, or use a conventional organic liquid electrolyte, which is toxic and flammable. The use of oxygen and moisture-sensitive electrolytes especially presents challenges for packing and sealing 3D printable batteries.To overcome these challenges, this work incorporated the latest developments in aqueous batteries into a novel 3D printable battery that can be fabricated directly in an ambient environment that is also more environmentally friendly in nature. Specifically, a gel polymer electrolyte (GPE) with a water-in-salt (WIS) concept was introduced in our 3D printed batteries. The WIS concept, using a highly concentrated electrolyte, offers a larger operation voltage compared with conventional aqueous batteries, whereas the GPEs formulation enables the printability and easier packaging than liquid counterparts. By combining the advantages of both WIS and GPE, the resulting 3D printable batteries show promise for much more simplified processing conditions, as well as performance. The structural, (electro-)chemical, and morphological evolution of the printed batteries are being investigated by synchrotron X-ray techniques and electrochemical analysis. Overall, our research explores the possibility for an easier and more environmentally friendly way to build 3D printable, customizable batteries for future technologies.