New electrode architecture, in which a polymer wall exists in the gap between interdigitated current collectors on SiO2/Si substrate, was developed for micro lithium-ion batteries with high power and high capacity. The polymer wall with 30μm thickness was very helpful to construct 3D Li4Ti5O12 composite anode and 3D LiCoO2 composite cathode with an aspect ratio of ∼0.5, resulting in a great improvement of cell capacity up to 270μAhcm−2 from 4.8μAhcm−2 of the cell previously prepared by sol–gel process for LiMn2O4 cathode and Li4Ti5O12 anode on a conventional non-wall electrode substrate. Furthermore, in the developed cell configuration with poly(methyl methacrylate) (PMMA) gel electrolyte, more than 60% of the discharge capacity at 2C rate was retained at 20C rate.