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

Abstract

Potassium-doped NaV6O15 thin films have been grown on fluorine-doped tin oxide (FTO) conductive glass using a simple low-temperature liquid-phase deposition method and through the annealing process. X-ray photoelectron spectroscopy revealed that potassium ions were successfully doped in NaV6O15 thin films. The kinetics analysis based on cyclic voltammetry measurements showed that the doped potassium ions enhanced the Na+ intercalation behavior and induced the formation of a new phase. Moreover, high-resolution transmission electron microscopy further verified the formation of the new phase. The annealed doped films exhibited excellent structural stability during cycling. With these benefits, the capacities of the film electrodes annealed at 400 and 450 °C were maintained to be 83.24 and 188.16% after 100 cycles, respectively. The surprising capacity growth of the doped film annealed at 450 °C can be attributed to the phase transition from NaV6O15 to NaV3O8. The discharge–charges profiles further showed that the capacity first increased and then decreased during the charging/discharging process. Also, the chronoamperometry curve test revealed that the Na+ transference number of the NaClO4/PC electrolyte was 0.077. Due to the synergistic effect of NaV3O8 and NaV6O15, the film showed capacity growth instead of capacity fading. It is the doped potassium ions that prevent the structural collapse, ensuring that the phase transition can be smoothly carried out during the cycles. Our research presents an effective way for improving electrode materials with a long cycle life.

Synergistic Effect of Composite V2O5/Ca0.17V2O5 Film Electrodes as High-Performance Cathodes of SIBs

“…Figure a displays the characteristic peaks of Ca, Na, V, O, and C, which prove their coexistence directly. The XPS in Figure b proves that Ca 2+ is successfully induced in the film, the Ca 2p peaks locate at 346.5 eV (2p 3/2 ) and 350.0 eV (2p 1/2 ), which is consistent with previous literature. , The XPS of V 2p is displayed in Figure c, peaks at 515.7 and 517.1 eV correspond to the contribution from V 4+ 2p 3/2 and V 5+ 2p 3/2 , respectively. ,, While the deconvoluted peaks located at 522.2 and 524.0 eV correspond to the V 4+ 2p 1/2 and V 5+ 2p 1/2 , respectively. ,, The integral peak area of V 5+ /V 4+ is 1.937, which can be attributed to the Ca 2+ existing in the interlayer positions, which can neutralize part of the negative charge and cause a partial conversion of V 5+ to V 4+ . The O 1s spectra in Figure d can be further fitted as three peaks at 529.08, 529.90, and 530.82 eV corresponding to the V–O bond, chemisorbed CO, and ambient OH, respectively. , …”

“…It is urgent to develop and utilize energy storage materials with excellent performance due to the developing modern life and the growing energy demand. , In the past few decades, lithium-ion batteries (LIBs) have made great progress because of high capacity, long cycling life and environmental friendliness, − they show promise in mobile electronic devices and electric vehicles. , However, their limits of cost and resource have restricted further application. − Given the abundance of resources, low cost, and nonpollution, sodium-ion batteries (SIBs) hold great promise to replace LIBs. , SIBs possess similar chemical properties and mechanisms of ion insertion/extraction as LIBs and are considered as the most suitable candidates for LIBs. − …”

De-Ammonium Ba0.18V2O4.95/NH4V4O10 Film Electrodes as High-Performance Cathode Materials for Magnesium-Ion Batteries

“…This is consistent with the phase transition results of NH 4 V 4 O 10 in the XRD patterns. The absorption peak in the range of 970–1100 cm –1 is the classical stretching vibration mode with the VO bond. , Moreover, the absorption peak at 878 cm –1 is the classical stretching vibrational mode of the V–O–V bond. , This is the diversification of the vanadium–oxygen bonds due to the phase transformation triggered by the increase in temperature. This result complements the XRD results and together explains the effect of annealing temperature on the structure of films.…”

“…The absorption peak in the range of 970−1100 cm −1 is the classical stretching vibration mode with the V�O bond. 38,39 Moreover, the absorption peak at 878 cm −1 is the classical stretching vibrational mode of the V−O−V bond. 34,40 This is the diversification of the vanadium−oxygen bonds due to the phase transformation triggered by the increase in temperature.…”

Synthesis and Electrochemical Performance of V6O13 Nanosheets Film Cathodes for LIBs

“…This can be attributed to the morphology and crystallinity determined by the annealing temperature, the crystallinity annealed at 450 °C becomes complete, and the lithium ions are difficult to insert/extract. In addition, a slight shift of peak position is observed with the increasing scan rate, which is mainly due to the polarization effect [ 36 , 37 ]. From the CV curves at different scan rates, the diffusion coefficient of Li + in the V 6 O 13 film electrode would be calculated from the peak current ( I p ) and scan rate.…”