Recent advances and future challenges in printed batteries

The continuous advances in smart and multifunctional materials and the corresponding growth of the Internet of Things require novel battery concepts with improved integration in different substrates and devices, leading to more efficient energy storage devices with higher power and energy density. These new batteries can be obtained through printing technologies, as they present interesting characteristics such as being thin, flexible, low cost and eco-friendlier, for an increasing number of applications such as smart cards, radio-frequency identification, portable medical diagnostic systems and sensors, among others. Further, printing technologies allow simple and low-cost up-scaling and, therefore, rapid technology transfer. The present review summarizes the recent advances in 2D and 3D printed batteries. 2D and 3D printing technologies are summarized and the state of the art on printed batteries is presented, divided by lithium batteries, Zn/MnO2 batteries, and other battery types. In recent years, printed batteries are being intensively developed by 3D printing technologies, where further developments in ink properties, compatibility with the manufacturing process and integration with devices are still required. In this context, the future challenges in the area of printed batteries are also presented and discussed.