The orientation and hybridization of ultrathin two-dimensional (2D) nanostructures on interdigital electrodes is vital for developing high-performance flexible in-plane micro-supercapacitors (MSCs). Despite great progress has been achieved, integrating CuSe and Ni(OH) 2 nanosheets to generate advanced nanohybrids with oriented arrangement of each component and formation of porous frameworks remains a challenge, and their application for in-plane MSCs has not been explored. Herein, the vertically aligned CuSe@Ni(OH) 2 hybrid nanosheet films with hierarchical open channels are skillfully deposited on Au interdigital electrodes/polyethylene terephthalate substrate via a template-free sequential electrodeposition approach, and directly employed to construct in-plane MSCs by choosing polyvinyl alcohol−LiCl gel as both the separator and the solid electrolyte. Because of the unique geometrical structure and combination of intrinsically conductive CuSe and battery-type Ni(OH) 2 components, such hybrid nanosheet films can not only resolve the poor conductivity and restacking problems of Ni(OH) 2 nanosheets but also create the 3D electrons or ions transport pathway. Thus, the in-plane MSCs device fabricated by such hybrid nanosheet films exhibits high volumetric specific capacitance (38.9 F cm −3 ). Moreover, its maximal energy and power density can reach 5.4 mW h cm −3 and 833.2 mW cm −3 , superior to pure CuSe nanosheets, and most of reported carbon materials and metal hydroxides/oxides/sulfides based in-plane MSCs ones. Also, the hybrid nanosheet films device shows excellent cycling performance, good flexibility, and mechanical stability. This work may shed some light on optimizing 2D electrode materials and promote the development of flexible in-plane MSCs or other energy storage systems.

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Aqueous multivalent ion batteries, especially aqueous zinc-ion batteries (ZIBs), have promising energy storage application due to their unique merits of safety, high ionic conductivity, and high gravimetric energy density. To improve their electrochemical performance, polyaniline (PANI) is often chosen to suppress cathode dissolution. Herein, this work focuses on the zinc ion storage behavior of a PANI cathode. The energy storage mechanism of PANI is associated with four types of protonated/non-protonated amine or imine. The PANI cathode achieves a high capacity of 74 mAh g−1 at 0.3 A g−1 and maintains 48.4% of its initial discharge capacity after 1000 cycles. It also demonstrates an ultrahigh diffusion coefficient of 6.25 × 10−9~7.82 × 10−8 cm−2 s−1 during discharging and 7.69 × 10−10~1.81 × 10−7 cm−2 s−1 during charging processes, which is one or two orders of magnitude higher than other reported studies. This work sheds a light on developing PANI-composited cathodes in rechargeable aqueous ZIBs energy storage devices.

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