Rechargeable aqueous zinc-ion batteries are highly desirable for grid-scale applications due to their low cost and high safety; however, the poor cycling stability hinders their widespread application. Herein, a highly durable zinc-ion battery system with a NaVO·1.63HO nanowire cathode and an aqueous Zn(CFSO) electrolyte has been developed. The NaVO·1.63HO nanowires deliver a high specific capacity of 352 mAh g at 50 mA g and exhibit a capacity retention of 90% over 6000 cycles at 5000 mA g, which represents the best cycling performance compared with all previous reports. In contrast, the NaVO nanowires maintain only 17% of the initial capacity after 4000 cycles at 5000 mA g. A single-nanowire-based zinc-ion battery is assembled, which reveals the intrinsic Zn storage mechanism at nanoscale. The remarkable electrochemical performance especially the long-term cycling stability makes NaVO·1.63HO a promising cathode for a low-cost and safe aqueous zinc-ion battery.

Aqueous zinc-ion batteries attract increasing attention due to their low cost, high safety, and potential application in stationary energy storage. However, the simultaneous realization of high cycling stability and high energy density remains a major challenge. To tackle the above-mentioned challenge, we develop a novel Zn/VO rechargeable aqueous hybrid-ion battery system by using porous VO as the cathode and metallic zinc as the anode. The VO cathode delivers a high discharge capacity of 238 mAh g at 50 mA g. 80% of the initial discharge capacity can be retained after 2000 cycles at a high current density of 2000 mA g. Meanwhile, the application of a "water-in-salt" electrolyte results in the increase of discharge platform from 0.6 to 1.0 V. This work provides an effective strategy to simultaneously enhance the energy density and cycling stability of aqueous zinc ion-based batteries.

demonstrated to be effective in enhancing the capacitance of carbon-based materials. For example, N, [4,6] O [7,8] and S [9,10] are the most well studied dopants for carbon-based materials. The functions of these dopants depend on their chemical environments in the carbon host structure and they can improve the capacitive performance of carbon-based materials in different manners. It has been reported that the negatively charged pyridinic N and pyrrolic N can serve as faradaic reaction sites and contribute pseudocapacitance, whereas the positively charged quaternary N can facilitate electron transport in carbon lattice. [7,11] The introduction of O and S doping can increase pseudocapacitance and improve the electrode surface wettability. [12,13] Recently, dual and multi ple heteroatom doping carbon materials have been developed and achieved excellent capacitive performance. [14][15][16] Pore engineering is another effective approach to enhance the capacitive performance of carbonbased materials. [17] First, the introduction of pores, especially micropores, can significantly increase the surface area of carbon materials. Second, the pores function as electrolyte reservoirs that can shorten ion diffusion length. Third, the rational construction of an interconnected network consisting of multiple scale pores can facilitate mass transport of ions. The combination of large surface area and efficient ion diffusion will increase the effective ion accessible surface area and therefore, the specific capacitance. This is particular important for ultrafast supercapacitors electrodes that aim to be operated at high charging/discharging rates. Despite that the pore engineering and elemental doping have been demonstrated separately on different carbon materials, the combination of these approaches has rarely been reported. Herein, we demonstrate a new porous carbon electrode with high level of structural complexity for ultrafast supercapacitors through the integration of tri-doping and pore engineering method in preparation of carbon-based electrodes. Results and DiscussionThe preparation of the N,O,S tri-doped hierarchical porous carbon foam is illustrated in Scheme 1. The precursors including graphene oxide (GO) nanosheets, Poloxamer 407 Carbonaceous materials are attractive supercapacitor electrode materials due to their high electronic conductivity, large specific surface area, and low cost. Here, a unique hierarchical porous N,O,S-enriched carbon foam (KNOSC) with high level of structural complexity for supercapacitors is reported. It is fabricated via a combination of a soft-template method, freeze-drying, and chemical etching. The carbon foam is a macroporous structure containing a network of mesoporous channels filled with micropores. It has an extremely large specific surface area of 2685 m 2 g −1 . The pore engineered carbon structure is also uniformly doped with N, O, and S. The KNOSC electrode achieves an outstanding capacitance of 402.5 F g −1 at 1 A g −1 and superior rate capability of 308.5 F g −1 at 100 A g −1...

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The high theoretical capacity and natural abundance of SiO 2 make it a promising high-capacity anode material for lithium-ion batteries. However, its widespread application is significantly hampered by the intrinsic poor electronic conductivity and drastic volume variation. Herein, a unique hollow structured Ni/SiO 2 nanocomposite constructed by ultrafine Ni nanoparticle (≈3 nm) functionalized SiO 2 nanosheets is designed. The Ni nanoparticles boost not only the electronic conductivity but also the electrochemical activity of SiO 2 effectively. Meanwhile, the hollow cavity provides sufficient free space to accommodate the volume change of SiO 2 during repeated lithiation/ delithiation; the nanosheet building blocks reduce the diffusion lengths of lithium ions. Due to the synergistic effect between Ni and SiO 2 , the Ni/SiO 2 composite delivers a high reversible capacity of 676 mA h g −1 at 0.1 A g −1 . At a high current density of 10 A g −1 , a capacity of 337 mA h g −1 can be retained after 1000 cycles.