α-Ni­(OH)2 is an ideal candidate material for a supercapacitor except for its low conductivity and poor stability. In this work, BO2 –-intercalated α-Ni x Co(1–x)(OH)2 is synthesized by a hydrothermal method at a low cost. The Co dopant can decrease the charge-transfer resistance and enhance the cyclic stability. The special unsaturated electronic state of BO2 – enhances the bonding with metal ions and attracts water molecules. Thus, the BO2 – ions support the hydroxide layers as pillars and create efficient paths for proton transportation, optimizing the utilization of α-Ni­(OH)2. The three-dimensional (3D) flowerlike morphology supplies an enormous number of active sites, and r-GO is added to improve the conductivity. As a result, the modified α-Ni­(OH)2 exhibits the specific capacitance of 2179, 1592, and 1423 F·g–1 at 1, 20, and 40 A·g–1, respectively, showing improved rate performance. Matching with the commercial activated carbon (AC) as an anode, the asymmetric capacitor delivers an energy density of 40.66 W·h·kg–1 when its power density is 187.06 W·kg–1. Meanwhile, it retains 81.5% capacitance of the initial cycle at 5 A·g–1 after 3000 cycles. With conductivity enhanced and structure stabilized, the modified α-Ni­(OH)2 confronts broader fields of application.

Although the lithium−sulfur battery has been developed for many years, how to restrain the intrinsic polysulfide shuttle is still a hot topic. Recently, it has been found that adding a multifunctional interlayer between cathode and separator can effectively inhibit the shuttle of polysulfides, while the lightweight factor of the interlayer commonly is ignored. In this work, a kind of lightly freestanding interlayer (0.16−0.4 mg cm −3 ) consisting of CeF 3 nanorod (prepared by in situ fluorination of CeO 2 nanorod in carbonization at 700 °C) and carbon nanotubes film (CF) is prepared. In this network structure, the CF network displays high electronic conduction and enhances the reaction kinetics for sulfur; CeF 3 can effectively adsorb polysulfides and enhance the cycle performance. Especially, the battery exhibits an initial specific capacity of 1505 mAh g −1 at 0.05 C, and the capacity decay after 100 cycles is only 0.063% per cycle. In addition, it retains a discharge capacity of 951 mAh g −1 over 100 cycles at 0.2 C and 542 mAh g −1 over 500 cycles at 1 C. Lightly freestanding CeF 3 /CNTs interlayer show a high application potential in the lithium−sulfur batteries.

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We prepared carbon-coated β-MnO2 for the cathode of a lithium-ion battery with high discharge capacity.