The fabrication of very high-aspect ratio 3D carbon microelectrodes for Li-Ion batteries is presented. Using a pyrolysis process under inert conditions, thick layers of patterned SU-8 photoresist (up to 600μm in height) are converted into carbon. The micro-structures resulting from this process are used as anode for a Li-Ion battery. A detailed explanation on how to create SU-8 structures of aspect ratios as high as 15:1 using UV light is provided. New shapes that are more mechanically stable during the pyrolysis shrinkage are introduced. Some insight into how to create these structures on top of copper foil used as a current collector is provided as well.