Good Lithium-Ion Insertion/Extraction Characteristics of a Novel Double Metal Doped Hexa-Vanadate Compounds Used in an Inorganic Aqueous Solution

Abstract

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.

Enhancement of Electrochemical Properties of SIBs by Generating a New Phase in Potassium-Doped NaV6O15 Film Electrodes

“…Among them, vanadium bronze materials (M x V 2 O 5 , M = metal ions) are regarded as promising cathodes due to their high capacity and low cost. , Most of them have notable electrochemical performance in lithium-, sodium-, magnesium-, and zinc-ion batteries − because of the three-dimensional tunnel structure that exhibits higher surface area, faster diffusion kinetics, and a more stable geometrical configuration upon cycling. − The typical vanadium bronze materials are LiVO 3 , LiV 2 O 5 , NaV 6 O 15 , K 0.5 V 2 O 5 , NH 4 V 4 O 10 , and so on. In our previous work, pure NaV 6 O 15 thin films have been successfully prepared and used in LIBs, which showed relatively excellent performance. , However, their cycling stability is often unsatisfactory due to the lowest content of supporting metal ions. , The solutions to this problem are listed below: (1) modifying the structure such as the incorporation of dopants and morphological control to improve capacity fading; − (2) compounding to achieve a synergistic effect; − and (3) coatings such as carbon coating to enhance the electronic conductivity and cycling stability. , Herein, doping has been chosen to improve the cycling stability of pure NaV 6 O 15 films in the work. In the structure of NaV 6 O 15 , the vanadium and oxygen atoms form layers, and sodium ions between V–O layers support the structure.…”

Enhanced Rate Capability and Cycling Stability of Novel Ammonium Vanadate Materials Used in Aqueous Li-Ion Batteries

“…When the scan rate is increased from 1 to 5 mVs −1 , the CV curves of NH 4 V 4 O 10 are greatly improved by increasing the overpotential differentiation between the two redox peaks. 41 Even with the scan rate increased to 5 mV s −1 , the redox peaks can still be visible, which means the material is capable of reaching high rates. A direct relationship can be made between the I p and V 1/2 for the microrod electrode material of NH 4 V 4 O 10 built on the CV values at various scan rates, as shown in Figure 5b, which clearly shows that the diffusion is controlled by reaction kinetics.…”

“…The representative redox peaks shift a bit to lower (reduction) and higher (oxidation) potentials and become broader. When the scan rate is increased from 1 to 5 mVs –1 , the CV curves of NH 4 V 4 O 10 are greatly improved by increasing the overpotential differentiation between the two redox peaks . Even with the scan rate increased to 5 mV s –1 , the redox peaks can still be visible, which means the material is capable of reaching high rates.…”

Excellent Rate Capability and Cycling Stability of Novel H2V3O8 Doped with Graphene Materials Used in New Aqueous Zinc-Ion Batteries

“…At the same time, energy storage systems, including batteries and capacitors, have experienced rapid development and popularization. 1 Traditional organic electrolyte lithium-ion batteries (LIBs) with high energy density are considered to be the most successful storage device in many fields such as electronic equipment, electric vehicles, and aerospace equipment. 2 However, the reliability of LIBs is increasingly doubted because of the scarcity of lithium resources and the flammability of the organic electrolyte.…”

“…In the past decade, many countries have introduced some policies and laws to encourage the development and utilization of renewable and green energy such as solar energy, wind energy, geothermal energy systems, and hydroelectric power to overcome the dependence on fossil fuels. At the same time, energy storage systems, including batteries and capacitors, have experienced rapid development and popularization . Traditional organic electrolyte lithium-ion batteries (LIBs) with high energy density are considered to be the most successful storage device in many fields such as electronic equipment, electric vehicles, and aerospace equipment .…”