Abstract: The invention provides plastic 3D printed battery cell comprising a first layer coupled with a cathode material and a second layer coupled with an anode material. An aqueous electrolyte gel material is deposited onto the surface of the cathode material and the anode material, wherein the first and second layers are sealed to house the cathode material, the anode material and the electrolyte gel material. The invention provides a combination of a customisable plastic battery cell design using 3D printing with an all-in-one gel electrolyte enable the cells to be built in a variety of sizes and shapes allowing for greater integration of energy storage into electronic, medical or wearable systems. A method for making the 3D printed battery cell is also described.