Manufacturing-oriented review on 3D printed lithium-ion batteries fabricated using material extrusion

The advent of conductive extrudable materials has broadened the range of additive manufacturing applications to include smart devices, circuits, actuators and sensors - all requiring electrical power. 3D printing of components dedicated to energy storage has also gained interest, with the goal of the monolithic printing of batteries directly integrated into subsuming smart components. This review focuses on the state of the art of extrusion-based 3D printed batteries, appearing as the most widespread, inexpensive and simple additive process. The paper is intended to introduce the processes and materials of 3D printing batteries, while highlighting the main manufacturing challenges and associated solutions proposed in literature. Particular attention is dedicated to describing the extrusion-based printers being employed and the required modifications, printing parameters and multi-material capabilities, with the aim of highlighting the most promising solutions required to print composite individual components and complete rechargeable batteries in a single non-assembly step.