One of the greatest technological challenges of today is efficient storage of electrical energy for portable applications, including electric vehicles, mobile electronic devices, and robotic systems. Further progress in these areas, however, is often hindered by the limitations of current rechargeable lithium ion battery technologies, which are among the most common power sources for these systems. Despite tremendous progress in electrode materials, the intrinsic drawbacks of current batteries are related to their planar two-dimensional design, which restrains the performance in terms of output power and charging speed. NANO-3D-LION is aimed to make a breakthrough in these major battery characteristics by a paradigm shift in battery engineering: the goal is to develop and employ advanced nanoscale 3D printing techniques to fabricate active battery materials with ultrasmall structural features, which will provide almost a thousand-fold increase in the surface area of the battery enabled by nanoscale spacing between its electrodes without compromising the battery capacity. To reach this, high-aspect ratio metal features will be fabricated and further converted into the active material of the cathode and the anode. This will enable unprecedented level of control of the battery architecture, allowing groundbreaking improvement of the key battery performance characteristics, including higher output power and charging times of only several seconds. NANO-3D-LION will establish a unique engineering approach with a potential to completely change the future landscape in research and industry related to portable electronic devices and electric vehicles and will also benefit many technologies beyond battery research, where nanoscale 3D printing opens new unparalleled capacity, therefore ensuring its broad scientific, economical and societal impact.