Nanorods of H2V3O8 wrapped in graphene sheets were prepared by hydrothermal synthesis and tested as the cathode in an aqueous rechargeable zinc-ion battery. Cyclic voltammetry indicates that H2V3O8 nanorods/graphene-523 K allows a rapid and reversible Zn2+ intercalation/extraction without the evolution of H2 and O2. The structure and composition of the composite graphene H2V3O8 nanorods [determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SEAD), and X-ray photoelectron spectroscopy (XPS)] offered excellent electrochemical performance including a high specific discharge capacity of 401 mAh g–1 at 200 mA g–1, a high rate capacity of 170 mAh g–1 at 2 A g–1, and prolonged cycling stability after 200 cycles. The addition of the graphene sheets increases the diffusion coefficient of the zinc ions by an order of magnitude. Five light-emitting diodes (LEDs) are successfully powered by the aqueous rechargeable zinc-ion batteries (ARZBs) for more than 2 min to demonstrate the practical application. This work provides a creative choice for energy storage applications with low prices, green and environmental protection, and excellent safety.

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We report a potassium doped NaV6O15 anode with enhanced electrochemical performance, used for aqueous rechargeable lithium ion battery. Different Na1–x K x V6O15 (x = 0, 0.1, 0.2, 0.3) compounds are prepared and characterized using X-ray diffraction patterns ensuring potassium doping. The electrochemical performances of the various potassium doped anodes NaV6O15, Na0.9K0.1V6O15, Na0.8K0.2V6O15, and Na0.7K0.3V6O15 are evaluated by cyclic voltammetry and galvanostactic charge/discharge methods. The results suggest that potassium-doping has a positive effect on the electrochemical performance of aqueous rechargeable lithium ion batteries. The anode Na0.8K0.2V6O15 is found to be optimized potassium doped anode materials for aqueous rechargeable lithium ion battery. The Na0.8K0.2V6O15 anode displays enhanced cycling and rate performances, an initial specific capacity of 218 mAhg–1, and 133 mAhg–1 is delivered after 50 cycles (61% capacity retention) at the current density of 100 mAg–1. The potassium doping has induced enhanced interlayer spacing in the layered structure of NaV6O15 due to potassium ions having larger ionic radii than sodium. This enhanced interlayer spacing provides wider channels for lithium-ion intercalation/extraction, which in turn increases the lithium-ion diffusion coefficient. The lithium-ion diffusion coefficients for NKVO-2 at 0.09, −0.26, and −0.68 V vs saturated calomel electrode (SCE) were calculated as 1.53 × 10–11, 1.29 × 10–11, and 8.90 × 10–12 cm2s–1, respectively.

A novel anode composite, carbon‐coated TiP2O7 nanoparticles (TPO@C) decorated with carbon nanotubes (CNTs), is fabricated through a simple sol–gel method and a calcination process for aqueous rechargeable lithium‐ion batteries (ARLBs). The complete interfacial contact of TPO@C and CNTs provides a 3D network structure with a high specific surface area. The effects of CNTs on the diffusion coefficient of lithium ions, rate performance, and cycle performance are investigated. Typically, the discharge capacities of the TPO@C/CNTs anode can reach up to 97.88, 93.86, 90.79, 86.54, and 77.42 mA h g−1 at the current densities of 0.2, 0.5, 1, 2, and 5 A g−1, respectively. At an extremely high current density of 10 A g−1, the discharge capacity over 800 cycles is almost as high as the initial discharge capacity. Moreover, a (TPO@C/CNTs)//LiMn2O4 full cell in saturated LiNO3 electrolyte is tested in a pouch cell. It also demonstrates a high reversible capacity of 83.51 mA h g−1 (≈60.42% capacity retention) after 1000 cycles at 2 A g−1. The results indicate that CNTs can promote the diffusion coefficient of lithium ions, and are responsible for the high rate performance and cycling stability.

An aqueous rechargeable lithium-ion battery (ARLB) system has been assembled using as-prepared polypyrrole (PPy) to coat Na0.8K0.2K6O15 (NKVO) anode coupled with LiMn2O4 cathode, both immersed in an aqueous LiNO3 solution.