Herein, the influence of the concentration design and comprehensive performance of the sulfate-phosphoric mixed acid system electrolyte is investigated to realize an electrolyte that maintains high energy density and ...Herein, the influence of the concentration design and comprehensive performance of the sulfate-phosphoric mixed acid system electrolyte is investigated to realize an electrolyte that maintains high energy density and stable operation at high temperatures. Static stability tests have shown that VOPO4 precipitation occurs only with vanadium(V) electrolyte. The concentration of vanadium ion of 2.0–2.2 mol·L^(–1), phosphoric acid of 0.10–0.15 mol·L^(–1), and sulfuric acid of 2.5–3.0 mol·L^(–1) are suitable for a vanadium redox flow battery in the temperature range from –20 to 50 ℃. The equations for predicting the viscosity and conductivity of electrolytes are obtained by the response surface method. The optimized electrolyte overcomes precipitation generation. It has 2.8 times higher energy density than the non-phosphate electrolyte, and a coulomb efficiency of 94.0% at 50 ℃. The sulfate-phosphoric mixed acid system electrolyte promotes the electrode reaction process, increases the current density, and reduces the resistance. This work systematically optimizes the concentrations of composition of positive and negative vanadium electrolytes with mixed sulfate-phosphoric acid. It provides a basis for the different valence states and comprehensive properties of sulfate-phosphoric mixed acid system vanadium electrolytes under extreme environments, guiding engineering applications.展开更多
The V_2C compound,belonging to the group of two-dimensional transition metal carbonitrides,or MXenes,has demonstrated a promising electrochemical performance in capacitor applications in acidic electrolytes;however,th...The V_2C compound,belonging to the group of two-dimensional transition metal carbonitrides,or MXenes,has demonstrated a promising electrochemical performance in capacitor applications in acidic electrolytes;however,there is evidence to suggest that V_2C is unstable in an acidic environment.On the other hand,the performance of V_2C in neutral aqueous electrolytes is still moderate,and has not yet been systematically studied.The charge storage mechanism in a V_2C electrode,employed in neutral aqueous electrolytes,is investigated via cyclic voltammetry testing and in situ x-ray diffraction(XRD).Good specific capacitances are achieved,specifically208 F/g in 0.5 M Li_2SO_4,225 F/g in 1 M MgSO_4,120 F/g in 1 M Na_2 SO_4,and 104 F/g in 0.5 M K_2SO_4.Using in situ XRD,we observe that,during the charge and discharge process,the c-lattice parameter shrinks or expands by up to 0.25 A in MgSO_4,and 0.29 A in Li_2SO_4 which demonstrates the intercalation/de-intercalation of cations into the d-V_2C layer.展开更多
We present a novel,low-cost optical sensor for accurate real-time monitoring of the state of charge(SoC)and total vanadium concentration in vanadium flow batteries.Using only six discrete wavelengths,the sensor achiev...We present a novel,low-cost optical sensor for accurate real-time monitoring of the state of charge(SoC)and total vanadium concentration in vanadium flow batteries.Using only six discrete wavelengths,the sensor achieves precision comparable to full-spectrum methods while significantly reducing equipment costs and complexity.A general deconvolution method is used to measure the SoC and the total vanadium concentration in both the negolyte and posolyte,with calibration covering concentrations from 1.21 to 1.82 mol/L.We achieve root mean square error(RMSE)values of 1.2%and 3.2%for the SoC,and 54 mmol/L and 97 mmol/L for the total vanadium concentration in the negolyte and posolyte,respectively,demonstrating excellent agreement with reference ultraviolet visible(UV-vis)data.In addition,a wavelength optimization study is proposed to determine the optimal number and placement of spectral channels,providing a basis for the design of tailored optical sensors for vanadium electrolytes.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51774216)Hubei Technical Innovation Special Project of China(Grant No.2017ACA185)Science and technology innovation Talent program of Hubei Province(Grant No.2022EJD002).
文摘Herein, the influence of the concentration design and comprehensive performance of the sulfate-phosphoric mixed acid system electrolyte is investigated to realize an electrolyte that maintains high energy density and stable operation at high temperatures. Static stability tests have shown that VOPO4 precipitation occurs only with vanadium(V) electrolyte. The concentration of vanadium ion of 2.0–2.2 mol·L^(–1), phosphoric acid of 0.10–0.15 mol·L^(–1), and sulfuric acid of 2.5–3.0 mol·L^(–1) are suitable for a vanadium redox flow battery in the temperature range from –20 to 50 ℃. The equations for predicting the viscosity and conductivity of electrolytes are obtained by the response surface method. The optimized electrolyte overcomes precipitation generation. It has 2.8 times higher energy density than the non-phosphate electrolyte, and a coulomb efficiency of 94.0% at 50 ℃. The sulfate-phosphoric mixed acid system electrolyte promotes the electrode reaction process, increases the current density, and reduces the resistance. This work systematically optimizes the concentrations of composition of positive and negative vanadium electrolytes with mixed sulfate-phosphoric acid. It provides a basis for the different valence states and comprehensive properties of sulfate-phosphoric mixed acid system vanadium electrolytes under extreme environments, guiding engineering applications.
基金Supported by the Science&Technology Department of Jilin Province (Grant Nos.20180101199JC and 20180101204JC)Jilin Province/Jilin University Co-construction Project-Funds for New Materials (SXGJSF2017-3)。
文摘The V_2C compound,belonging to the group of two-dimensional transition metal carbonitrides,or MXenes,has demonstrated a promising electrochemical performance in capacitor applications in acidic electrolytes;however,there is evidence to suggest that V_2C is unstable in an acidic environment.On the other hand,the performance of V_2C in neutral aqueous electrolytes is still moderate,and has not yet been systematically studied.The charge storage mechanism in a V_2C electrode,employed in neutral aqueous electrolytes,is investigated via cyclic voltammetry testing and in situ x-ray diffraction(XRD).Good specific capacitances are achieved,specifically208 F/g in 0.5 M Li_2SO_4,225 F/g in 1 M MgSO_4,120 F/g in 1 M Na_2 SO_4,and 104 F/g in 0.5 M K_2SO_4.Using in situ XRD,we observe that,during the charge and discharge process,the c-lattice parameter shrinks or expands by up to 0.25 A in MgSO_4,and 0.29 A in Li_2SO_4 which demonstrates the intercalation/de-intercalation of cations into the d-V_2C layer.
基金supported by Grant TED2021-129378B-C21 funded by MICIU/AEI/10.13039/501100011033by the“European Union NextGenerationEU/PRTR”support of an MCSA-Cofund“Energy for Future”postdoctoral research fellowship(E4F)from the Spanish Iberdrola Foundation(GA101034297)。
文摘We present a novel,low-cost optical sensor for accurate real-time monitoring of the state of charge(SoC)and total vanadium concentration in vanadium flow batteries.Using only six discrete wavelengths,the sensor achieves precision comparable to full-spectrum methods while significantly reducing equipment costs and complexity.A general deconvolution method is used to measure the SoC and the total vanadium concentration in both the negolyte and posolyte,with calibration covering concentrations from 1.21 to 1.82 mol/L.We achieve root mean square error(RMSE)values of 1.2%and 3.2%for the SoC,and 54 mmol/L and 97 mmol/L for the total vanadium concentration in the negolyte and posolyte,respectively,demonstrating excellent agreement with reference ultraviolet visible(UV-vis)data.In addition,a wavelength optimization study is proposed to determine the optimal number and placement of spectral channels,providing a basis for the design of tailored optical sensors for vanadium electrolytes.
