Three-dimensional self-supported metal oxides as cathodes for microbatteries

Microbatteries are currently the best choice to power microelecronic devices. To maximize both energy density and power density of microbatteries within the areal footprint, the three-dimensional (3D) microbattery architectures have been proposed, comprising a 3D matrix of components (cathode, anode and electrolyte) arranged in either a periodic array or an aperiodic ensemble. As one of the key components, the cathode is vital to the electrochemical performance of microbatteries and the fabrication of 3D cathode is still challenging. This review describes recent advances in the development of 3D self-supported metal oxides as cathodes for lithium-ion microbatteries. Current technologies for the design and morphology control of 3D cathode fabricated using template, laser structuring and 3D printing are outlined along with different efforts to improve the energy and power densities.