Batteries based on three dimensional microstructures are expected to offer significant advantages in comparison to conventional two dimensional batteries. One of the key elements for creating new types of 3D microbatteries is fabricating high-aspect-ratio carbon structures. Our efforts on building positive photoresist structures include: (1) casting photoresist in 3D molds made by DRIE before pyrolysis; (2) multi-exposure and multi-developing processes, and (3) using embedded masks in multi-layer photoresists. Another effort is the fabrication of high-aspect-ratio carbon structures using negative photoresist. We manufactured high-aspect-ratio (~10:1) carbon posts by pyrolysis from negative photoresists in a simple one-step process. Simulation results showed that current density is strongly influenced by the biasing pattern and the geometry of the electrodes themselves. Current density (and therefore power density) is stronger at the edge of electrodes-implying that closer spacing of the electrodes will provide a denser current concentration. Electrochemical tests demonstrate that these C-MEMS electrodes can be charged/discharged with Li. A C-MEMS battery approach has the potential to solve both manufacturing and materials problems simultaneously.