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Nickel compounds, especially Ni(HCO3)2 (here denoted as NiC), have been widely combined with other materials to obtain composites with a more favorable structure that exhibit excellent electrochemical performance as supercapacitors. Unfortunately, the complicated processes for preparing such composites directly restrict their further application. Herein, we prepared a NiC/nickel tetraphosphate (Ni(P4O11)) nanocomposite (NiC/NiP) by introducing ions into the NiC reaction system; this composite can be applied in high-performance supercapacitors. The micromorphology of NiC/NiP material displayed an appropriate combination of NiP nanowires and thin NiC nanosheets, which provide sufficient active sites, short ion diffusion paths and fast ion diffusion speeds. NiC/NiP material exhibited an excellent rate performance of 70.2% retained capacity, although the current was increased by 15 times (1196 F g−1 at 2.0 A g−1 and 840 F g−1 at 30 A g−1). The energy density of a NiC/NiP//active carbon (AC) asymmetric supercapacitor fabricated in 6 M KOH was as much as 39.02 W h kg−1 and 26.67 W h kg−1 under corresponding power densities of 160 W kg−1 and 8000 W kg−1, respectively. The asymmetric supercapacitor delivered a stable cyclic performance of 78% capacitive retention after 5000 continuous charge/discharge cycles. More importantly, a 2.5 V light-emitting diode was lit successfully by two NiC/NiP//AC asymmetric supercapacitors in series. These results confirm that NiC/NiP nanocomposite has great potential in practical applications of electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

PC-Zn@SSM electrode with prominent compatibility to seawater and optimized reaction interface demonstrates superior electrochemical performance. The in/ex-situ techniques were further conducted to reveal the working mechanism. [Display omitted] • Zn anode in-situ growth on SSM is prepared via in-system synthesis technique. • Interface regulation improves compatibility and mechanical stability of Zn anode. • Prepared Zn electrode shows excellent performance and anti-interference capability. • The dendrite-free self-regulation mechanism is verified via in/ex-situ techniques. • The assembled seawater Zn-air battery shows a maximum energy density of 285 Wh m−2. In this work, Zn anode with a high compatibility to seawater system is fabricated on stainless steel mesh using an ultra-simple in-system synthesis technique. Physical characterizations reveal that the film electrode is composed by cross-linked Zn nanoflakes structure with outstanding adhesion and mechanical deformation tolerance. Being adopted as seawater-compatible anode, the as-synthesized Zn electrode exhibits a high reversible capacity of 30 mAh cm−2 with obvious advantages such as outstanding rate capability, strong tolerance to real-time varied current, low capacity decay, and good long-term cycling stability. The assembled Zn-air battery performs a maximum energy density of 285 Wh m−2 and successfully lights up various electronic devices. Furthermore, the self-regulation working mechanism and the growth kinetic of Zn electrode are further investigated using in-situ optical microscopy observations and in-situ electrochemical impedance spectroscopy (EIS) techniques. This work demonstrates a promising feasibility for fabricating highly reversible and low-cost Zn electrode in seawater system aiming to large-scale energy storage. [ABSTRACT FROM AUTHOR]

• NME exhibits extremely moldability more than flexibility. • NME shows both excellent mechanical and electrochemical properties. • NME owns both energy storage and ORR catalytic activity. • Reaction mechanism of NME is studied by in-situ Raman and EIS. Herein bifunctional NiO moldable electrode (NME) is successfully fabricated which exhibits satisfied flexibility, moldability and ductility. The ultimate elongation of NME is 43.5% and the area can be spread to as high as 525%. As a bifunctional electrode, the NME can not only provide activity through its own NiOOH/NiO redox mechanism, but also continue to work as a catalytic cathode based on oxygen reduction reaction (ORR) catalysis, which greatly expands its application prospects. The NME-assembled single cell achieves extraordinary moldability and compatibility, which could maintain stable electrochemical performance while being arbitrarily cut or bent. More promisingly, the as-test Zn-air system further demonstrates its bifunction for energy storage, especially based on its good ORR catalytic activity for a longer running time. In-situ Raman technology is performed to further study the reaction dynamic of NME during the whole energy storage process. The development of bifunctional NME paves a new and promising avenue towards the future design of solid-state batteries. A bifunctional moldable NiO electrode exhibits excellent mechanical properties, meanwhile, it presents great energy storage activity and oxygen reduction reaction activity as cathode for both aqueous flexible solid-state energy storage devices and Zn-air system, and this work paves a promising avenue towards the future design of solid-state batteries. [Display omitted] [ABSTRACT FROM AUTHOR]