Scalable, Binderless, and Carbonless Hierarchical Ni Nanodendrite Foam Decorated with Hydrous Ruthenium Dioxide for 1.6 V Symmetric Supercapacitors

Herein, Ni nanodendrite (ND) with diameter ≈30–100 nm directly synthesized on Ni foam is utilized as an effective support for hydrous RuO 2 in symmetric supercapacitors operated at 1.6 V. Highest specific capacitance 678.57 F g −1 can be achieved with energy density 60.32 Wh kg −1 . Even at large current density 100 A g −1 , high energy density 19.73 Wh kg −1 can still be maintained with power density 40 kW kg −1 owing to the pristine metal nanostructure without any carbon additive and resistive binder. Long lifespan is shown with marginal performance improvement (≈4%) over 10 000 cycles. More importantly, the template‐less and self‐assembled Ni ND synthesis requires only low temperature and eco‐friendly chemicals, and can be simply dip‐coated with RuO 2 nanoparticles. All of these render the RuO 2 ‐Ni ND foam readily adapted into mass manufacturing without efforts.