**2.1 Printed battery technology**

Printed batteries can be in the form of rechargeable and non-rechargeable printed batteries. These printed batteries can be classified based on the make of the electrochemical systems as rechargeable and non-rechargeable printed batteries as shown in **Figure 2** [8]. The printing paste for batteries is made up of the electroactive material, the solvent, the conductive agent and the binder. The advantages of printed batteries include (1) it is possible to develop more than one layer pattern of design in the battery fabrication [9, 10], (2) Low cost and mechanically flexible batteries [11], (3) Thin and flexible energy storage [12] and (4) compatibility with the printing processes and devices [13]. Printed battery technologies find applications in the Internet of Things (IoT) devices [5], wearable electronic devices, smart cards, remote sensors, medical devices [9], microelectromechanical systems (MEMS) devices, low-power microprocessors, big-data analytics [14], electric vehicles, stationary storage grids [15], renewable energy and smart grid [16], etc.
