The growing market of small consumer electronics, such as cell phones, smartwatches or electronic eyewear requires development of small power sources that allow for both satisfactory usage time and fast charging. Lithium-ion batteries (LIBs) are currently the systems of choice thanks to their high energy and power density. However, downscalling these batteries for small device applications still possess a big challenge. Thin-film Li-ion micro-batteries with high (dis)charging rate capability are currently available on the market, but are limited to niche applications such as chip backup power as the total output energy are still far too low for consumer device applications. Also, the manufacturing of thin film batteries requires sophisticated PVD/CVD deposition techniques. To overcome these issues, 3D architecturing of the current collector can be employed [1, 2]. This can provide a system where very thin active materials are stacked over enormously large surface area of a 3D current collector to yield a cell with both high power density (due to reduced materials thickness) and high energy density (thanks to large total volume of the active materials). To minimize the dead volume, it is imperative that the current collectors are both small and have controlled spacing. Herein, we report on the fabrication of ordered nickel nano-mesh (Fig. 1a). The nanostructured cathode is prepared by cost effective electrodeposition method, using anodized aluminum oxide (AAO) as a template for 3D interconnected nanowires. A nickel nanowire mesh with 30 nm-wide nanowires and 80 nm spacing is shown in Fig. 1a. Further, we demonstrate an accurate method to determine the effective surface area based on the electrochemical passivation of nickel. In this example, the current collector contains 71% of empty volume and has the total surface area enhancement reaching up to 97x for the 2.7 μm-long 3D nanoscaffold in Fig. 1a. Next, 25 nm of manganese dioxide was electroplated on the Ni nano-mesh current collector (Fig. 1b). The thin film cathode layer showed 82x higher current and 66x higher charge for lithium extraction in Li⁺/PC electrolyte as compared to 65nm planar MnO₂ electrode (Fig. 1c). Additionally to electrochemical performance, we will discuss the methods we used to mitigate material incompatibility between the current collector and active material during thermal processing, needed for good crystallization of the electroactive layers. Backed with simulation and grazing-incidence XRD data, we will stress the importance of appropriate interface engineering for fabrication of reliable nickel-based nanostructured electrodes.

1. J. F. M. Oudenhoven, L. Bagetto, P. H. L. Notten, Adv. Energy Mater., 2011, 1, p. 10-33.

2. J.Vanpaemel, A. M. Abd-Elnaiem, S. De Gendt, P. Vereecken, J. Phys. Chem. C, 2015, 119 (4), pp 2105-2112