Hierarchical nanostructures with highly exposed active surfaces for high‐performance pseudocapacitors have attracted considerable attention. Herein, a one‐step growth of (Ni _xCo_1−x)₉Se₈ solid solution series in various conductive substrates as advanced electrodes for flexible, foldable supercapacitors is developed. The formation of (Ni_xCo_1−x)₉Se₈ solid solution is confirmed by Vegard's law. Interestingly, the as‐grown (Ni_xCo_1−x)₉Se₈ solid solution series spontaneously crystallized into nanodendrite arrays with hierarchical morphology and fractal feature. The optimized (Ni_0.1Co_0.9)₉Se₈ nanodendrites deliver a specific capacitance of 3762 F g⁻¹ at a current density of 5 A g⁻¹ and remains 94.8% of the initial capacitance after 5000 cycles, owing to the advantage from fractal feature with numerous exposed () surface as well as fast ion diffusion. The as‐assembled flexible (Ni_0.1Co_0.9)₉Se₈@carbon fiber cloth (CFC)//PVA/KOH//reduced graphene oxide@CFC device exhibits an ultrahigh energy density of 17.0 Wh kg⁻¹@ 3.1 kW kg⁻¹, outperforming recently reported pseudocapacitors based on nickel‐cobalt sulfide and selenide counterparts. This study provides rational guidance toward the design of fractal feature with superior electrochemical performances due to the significantly increased electrochemical active sites. The resulting device can be easily folded, pulled, and twisted, enabling potential applications in high‐performance wearable and gadget devices.

中文翻译：

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具有高暴露（）表面的分形（NixCo1-x）9Se8纳米树枝状阵列，可穿戴全固态超级电容器

高性能伪电容器的有源表面高度暴露的分层纳米结构引起了广泛的关注。在本文中，开发了（Ni _x Co _{1- x}）₉ Se ₈固溶体系列在各种导电衬底中的一步生长，作为柔性，可折叠超级电容器的高级电极。（Ni _x Co _{1- x}）₉ Se ₈固溶体的形成通过维加德定律得以证实。有趣的是，刚生长的（Ni _x Co _{1− x}）₉ Se ₈ 固溶体系列自发地结晶成具有分级形态和分形特征的纳米枝晶阵列。优化的（Ni _0.1 Co _0.9）₉ Se ₈纳米枝晶在5 A g ^-1的电流密度下可提供3762 F g ^-1的比电容，并且由于分形的优势，在5000次循环后仍保持初始电容的94.8％。具有众多暴露（）表面的特征以及快速的离子扩散。组装后的柔性（Ni _0.1 Co _0.9）₉ Se ₈@碳纤维布（CFC）// PVA / KOH //还原氧化石墨烯@CFC装置的超高能量密度为17.0 Wh kg ^-1 @ 3.1 kW kg ^-1，优于最近报道的基于镍钴硫化物和硒化物的伪电容器同行。由于显着增加的电化学活性位，这项研究为具有优异的电化学性能的分形特征的设计提供了合理的指导。由此产生的设备可以轻松折叠，拉动和扭曲，从而在高性能可穿戴设备和小工具设备中实现潜在的应用。