Construction of ultrahigh capacity density carbon nanotube based MIM capacitor

Energy storage technology is a key for a clean and sustainable energy supply. but their energy density is restricted by surface charge storage. One effective way to enhance the energy density is electrodes nanosizing in constructing MIM capacitor. However, the overall performance of the capacitors is still limited by electrode specific surface area and bonding strength of their electrode nano-templates to the substrate. In this work, the spatial multilayer VCNTs electrode nano-templates were obtained by laser etching assistance, and MIM capacitors were constructed layer-by-layer with SnO₂/Al₂O₃/SnO₂ structures as the dielectric capacitor frameworks via ALD. Laser etching is demonstrated on Al substrate, allowing the spatial multilayer growth of VCNTs with ultrahigh electrode area. Laser etching also introduces an Al₂O₃ buffer layer, which induces VCNTs in-situ growth during CVD and ensures bonding strength to Al substrate. Moreover, the VCNTs facilitates more coverage by dielectric during ALD, thus reducing the micro-short circuits risk for capacitors. Impressively, the fabricated MIM capacitors have high planar capacity density (0.47∼1.92 mF/cm²) with a low leakage characteristic (5.7 × 10⁻⁷ A/cm²) at 1V, which could reach a high energy density (26 µWh/cm²) and power density (104 W/cm²), as well as excellent performance stability under atmospheric and water environments. This work shows a promising strategy for developing new energy storage devices with both high energy and power density, and it has important guiding significance for the electrode nano-templates materials design and preparation of energy storage devices.