3D microbatteries are proposed as a step change in the energy and power per footprint of surface mountable rechargeable batteries for microelectromechanical systems (MEMS) and other small electronic devices. Within a battery electrode, a 3D nanoarchitecture gives mesoporosity, increasing power by reducing the length of the diffusion path; in the separator region it can form the basis of a robust but porous solid, isolating the electrodes and immobilising an otherwise fluid electrolyte. 3D microarchitecture of the whole cell allows fabrication of interdigitated or interpenetrating networks that minimise the ionic path length between the electrodes in a thick cell. This article outlines the design principles for 3D microbatteries and estimates the geometrical and physical requirements of the materials. It then gives selected examples of recent progress in the techniques available for fabrication of 3D battery structures by successive deposition of electrodes, electrolytes and current collectors onto microstructured substrates by self-assembly methods.

An easy method, cost effective, and scalable approach was developed for the preparation of graphene nanosheets. Graphene oxide (GO) was synthesized by modified Hummer method, and thermal reduction was performed in air ambient at 350°C. The results of Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) spectroscopy indicate that GO is reduced to graphene. A perfect hexagonal GO structure was confirmed by high resolution transmission electron microscope (HRTEM) images. After thermal reduction, few layers of thermally reduced graphene oxide (TRGO) with dimension of hundred nanometers were obtained. The electrochemical properties of the graphene nanosheets as electrode materials for supercapacitors were studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Higher specific capacitance of 731 F g⁻¹ in 1M H₂SO₄ at a scan rate of 10 mV s⁻¹, and a large specific capacitance of 451 F g⁻¹ was preserved at high scan rate of 100 mV s⁻¹.