The Investigation On Physicochemistry Property Of Vanadium Solution(?)/(?)

Vanadium redox flow battery(VRFB)has received a widespread attention from all walks of life as a new kind of environmental and large scale energy storage technology nowadays which renewable energies such as wind and solar have a rapidly growth.Vanadium battery electrolyte is an electric conduction as well as electroactive material for energy storage,which also the core of transformation and storage of energy.In this paper,thermodynamic properties of aqueous solution of V(IV)and V(V)in which concentration is relatively rare has been investigated by conductivity method for a clearer cognition on the existence form of vanadium,the variation of solution linked to temperature and form,which can provide requisite support for optimized proportioning of electrolyte and setting of rational charging-discharging order.The conductivities of aqueous VOSO4 with various molalities are measured in the temperature range from 278.15 to 318.15 K,the limiting molar conductance A0 and the dissociation constant of ion-pair[VOSO4]0 Kd in the solution are determined at different temperature according to Fuoss's method and Shedlovsky's method.It is found that limiting molar conductance has heightened as the temperature increased;meanwhile the dissociation constant has reduced.On the basis of the empirical equation of the relationship between dissociation constant and temperature,the values of other thermodynamic functions for the dissociation process of the ion-pair[VOSO4]0 are obtained:?G0>0 indicates that the ion-pair dissociation reaction cannot occur spontaneously under the condition of constant temperature and pressure,?S0<0 means dissociation entropy is the resistance of the dissociation process while dissociation enthalpy is the driving force due to ?H0<0.Furthermore,dissociation process mechanism of ion pair has been discussed according to its thermodynamic functions and it is deduced that hydration between water molecules and VO2+ in solvents is the key of the whole dissociation pocess.Finally,values of ionic limiting molar conductivity,stocks radius,the transport number,and diffusion coefficient for ion VO2+ are estimated at various temperatures,and all these parameters are increasing as the heightening of temperature except the stocks radius.The conductivities of aqueous solution V(V)sulfuric acid which belong to ternary system with various molalities are measured in the temperature range of 278.15?318.15 K.The conductivities of V(V)+H2SO4+H2O belonging to the ternary system is converted into the conductivities binary system V(V)aqueous solution by the method of extrapolation,the effects of concentration and temperature on thermodynamic properties of V(V)aqueous solution have been studied from many aspects including values of ionic limiting molar conductivity,stocks radius,the transport number,diffusion coefficient and conductance activation energy.It indicates that values of limiting molar conductivity of solution,ionic limiting molar conductivity,diffusion coefficient and the transport number for ion VO2+,are increasing while stocks radius is inverse as the heightening of temperature.Conductance activation energy of VO2+ is decreasing as the larger concentration of V(V).