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An essential key to enhance the redox chemistry of battery-type materials is to construct rational design of nanoarchitectures with high electrochemical activity. Herein, we reported a hierarchical composite consisting of bilayered nickel hydroxide carbonate nanoplates-decorated nanoflowers on nickel foam (NHC NPs@NFs/Ni foam) via a facile homogeneous precipitation method for use as an effective cathode in hybrid supercapacitors (HSCs). Under controlled growth time (4 h), the bilayered NHC NPs@NFs with hierarchical alignment were spontaneously crystallized on Ni foam. The as-preapared hybrid structure greatly enhanced the electroactive surface area and enabled the rapid redox chemistry in alkaline electrolyte. Notably, the hybrid NHC NPs@NFs/Ni foam delivered a maximum areal capacity of 727.4 μAh/cm 2 at 2 mA/cm 2 and it is relatively higher than its oxide form (76.6 μAh/cm 2 ) in a three-electrode system. Also, a pouch-type HSC with bilayered NHC NPs@NFs/Ni foam and porous carbon electrodes was fabricated, which demonstrated superior energy storage performance in terms of capacitance (1445.8 mF/cm 2 ), energy density (0.506 mWh/cm 2 ), power density (35.675 mW/cm 2 ) and cycling stability (89.4%). Furthermore, the self-charging power station consisting of a solar cell for energy conversion and the HSCs for energy storage was also assembled to operate the portable electronic displays and wall clock effectively for long time. This facile approach for the cost-effective fabrication of hierarchically designed nanomaterials paves a path for the development of high-performance hybrid supercapacitors. [ABSTRACT FROM AUTHOR]

We introduce a “gelating-cutting” strategy to improve specific areal capacity and cycle life for Li-O 2 cathode. Conventional Li-O 2 cathode with liquid electrolyte is gelated with highly elastic crosslinked polymer and cut into 50–200 µm granules. The gaps between the packed gel granules efficiently induce oxygen to the inner part of the cathode, leading to even Li 2 O 2 growth in thick cathode. Meanwhile, the elasticity of the polymer chain helps to keep good contact between carbon and Li 2 O 2 nanoparticles, which facilitates the electron transfer and improves the cyclability. Without any catalyst, the granular gel cathode is able to run 170 cycles at a fixed capacity of 1000 mA h g carbon −1 , or maintains a specific capacity higher than 10,500 mA h g carbon −1 (12.6 mA h cm −2 ) during 11 cycles of full discharge-charge. Since good contact is the precondition to any electrochemical reaction, our strategy is a general way to enhance the performance of Li-O 2 cathodes. [ABSTRACT FROM AUTHOR]

Developing electrodes cycling stably at high areal mass loadings is critical for sodium ion batteries (SIB) to reach practical applications, but remains challenging due to the larger ionic radius of Na+ and generally sluggish electrochemical kinetics in thick electrodes. Consequently, most of the reported SIB electrodes exhibit low mass loadings (<1 mg cm−2) and thereby limited areal capacities. Here, we develop a hybrid network structure with orthorhombic Nb 2 O 5 coatings sandwiched between three-dimensional carbon nanotube (CNT) underlayers and outer carbon shells. By thickening Nb 2 O 5 intermediate layers, we can effectively raise the mass loadings of the sponge anodes with the electron and ion transport kinetics well maintained, owing to the highly conductive CNT substrate, porous network and carbon shell-enabled robust nanocable structures. As a result, the sponge anodes exhibit reversible areal capacities of 2.7 mAh cm−2 after 200 cycles at mass loadings up to 16.6 mg cm−2, exceeding 9 times those of previous Nb 2 O 5 -based structures, and the achieved cycling stability is also among the best of the high-areal-capacity SIB anodes reported so far. Our work shows that thickening intermediate active coatings in rationally designed nanocable structures represents an effective way to promote their areal sodium storage performance for practical use. Image 1 • Three-dimensional network structured electrode composed of interconnected nanocables. • Nanocable comprises carbon nanotube core, Nb 2 O 5 intermediate layer and carbon shell. • Thickening intermediate layer to raise electrodes mass loadings and areal capacities. • Robust hierarchical structure enables stable cycling performance for sodium storage. [ABSTRACT FROM AUTHOR]