Membraneless Flow Batteries Based On Hydrophobic Ionic Liquid/aqueous Immiscible Two-phase Electrolytes

With the development of science and technology,energy consumption is increasing,and the shortage of resources will eventually become one of the important problems that people are facing.So far,many methods have been put forward and tried.The conventional energy,such as coal,oil,natural gas,was developed and utilized by people in the early days.The excessive consumption of resources led to energy exhaustion,and the combustion of fossil fuels would also produce harmful gases and cause environmental pollution.So people turn to look for clean and renewable energy.Such as wind energy,solar energy,etc.Wind energy and solar energy are inexhaustible,clean and clean energy provides development prospects.But wind energy and solar energy can only play a role in the wind and sunlight,with intermittent characteristics,can not meet the power supply needs of different periods,easy to cause a waste of current.Therefore,looking for a stable way of energy storage and reasonable distribution of energy has become a new research direction.As a new energy storage technology,membrane free flow battery can store energy and use it as much as possible.The main characteristics of the membrane free flow battery are that the membrane in the traditional flow battery is removed,the battery structure is simplified,and the cost of the battery is reduced.The storage of electric energy is adjusted by adjusting the electrode area and capacity storage.It has the advantages of adjustable energy,high efficiency,high capacity,and easy access to safe green materials.Nowadays,many different flow batteries have been reported,but viologen compounds are often used in the study of flow batteries because of their simple synthesis steps and high yield.However,most of the viologen derivatives are used as electroactive substances in inorganic phase.Based on this,this paper will study the viologen derivatives dissolved in organic phase and explore their electrochemical behavior,The film free flow battery was prepared(1)It was modified by the molecular structure of viologen“Four kinds of viologens with different structures were prepared by S_N2 substitution,and symmetrical and asymmetric viologens were constructed respectively.Butyl and benzyl groups were selected as the substituents of viologen,which improved the solubility of viologen in organic phase and avoided reducing the electrochemical migration rate of viologen derivatives in ionic liquids due to too large substituents.(2)In this experiment,hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was selected as the anode electrolyte of battery.The solubility and electrochemical behavior of viologen compounds in ionic liquid were proved by experimental test and electrochemical method,and the stability and reversibility of viologen compounds were proved.(3)The inorganic phase is saturated with potassium hexafluorophosphate solution,and the organic phase ionic liquid can be naturally layered under the action of gravity.The distribution performance is studied.The results show that there is no cross contamination between the organic phase and the inorganic phase.By selecting the open circuit voltage formed between cathode and anode,the flow battery was assembled.The test results show that the constructed flow battery can still maintain high coulomb efficiency and voltage efficiency after multiple cycles.