The three-dimensional (3D) structure of batteries nowadays obtains a lot of attention because it provides the electrodes a vast surface area to accommodate and employ more active material, resulting in a notable increase in areal capacity. However, the integration of polymer electrolytes to complicated three-dimensional structures without defects is appealing. This paper presents the creation of a flawless conformal coating for a distinctive 3D-structured NiO/Ni anode using a simple thermal oxidation technique and a polymer electrolyte consisting of three layers of PAN-(PAN-PVA)-PVA with the addition of Al2O3 nanoparticles as nanofillers. Such a composition with a unique combination of polymers demonstrated superior electrode performance. PAN in the polymer matrix provides mechanical stability and corrosion resistance, while PVA contributes to excellent ionic conductivity. As a result, NiO/Ni@PAN-(PAN-PVA)-PVA with 0.5 wt% Al2O3 NPs configuration demonstrated enhanced cycling stability and superior electrochemical performance, reaching 546 mAh g−1 at a 0.1 C rate.

In the era of miniaturization, micro energy storage devices become an essential part of the progress in many fields starting from simple sensors to medical devices. However upcoming developments in all these fields are restricted to finding safe, reliable and high-performance micro batteries with the shapes that is not limited only to rectangles, cylinders, and pouches. The research is confronted with challenges of fitting a battery into a microdevice. Lithium-ion batteries (LIBs), a mature energy storage technology, are a leading candidate for the development of micro batteries that can be easily integrated into microelectronic devices. However, despite significant achievements in the field of micro batteries, limitations in areal capacity and in power densities still motivate the search for alternative designs and novel concepts in the battery field. Insufficient areal energy density from planar micro batteries has inspired a search for three-dimensional micro batteries. The power output of a three-dimensional micro battery is expected to be higher than that of a two-dimensional battery of equal size, as a result of the higher ratio of electrode-surface-area to volume and lower Ohmic losses. Within a battery electrode, the 3D architecture provides large surface area, increasing power by reducing the diffusion path for Li ions. Additive manufacturing, also known as 3D printing, has appeared as a novel class of free form fabrication technologies that have a variety of possibilities for the rapid creation of complex architectures at lower cost than conventional methods. 3D printing enables the controlled creation of functional materials with three-dimensional architectures, representing a promising approach for the fabrication of next-generation electrochemical energy-storage devices and has many unique advantages over conventional manufacturing methods. In this work, printer is employed to print a 3D micro battery with MXene electrodes that can be printed easily and can be fitted into any small device.