Research On Chemical Power Source For Medicine Based On Ionic Liquid Electrolyte System

With the continuous progress of science and technology, the moden small-micro portable medical devices have get a rapid development, especially the electronic instruments which is in contact with the hunman body. Besides the requirement to the high performance of the medical devices, the chemical power source witch is used in them also should be improved. The cardiac pacemaker is an electronic intrusment, it is implanted in the hunman body and transmits pulse to make the heart shrink and renew the impaired heart function througu the energy supplied by the chemical power source which should have the characteristics of large capacity and steady discharge platform to reduce the numbers of replacement and enhance the stability of the pulse period. Potassium ferrate, as a new kind of high-capacity green cathode materials, has attracted much attention in the area of chemical power of medicine.The power source composed with the potassiumferrate and zinc exhibits high capacity and stable discharge platform, so it is suitable for the high-performance medical electronic equipments.Unfortunately, the stability of the potassium ferrate in the alkaline aqueous solution, so the development of the non-aqueous alkaline electrolyte is imperative.In this paper, two kinds of imidazole ionic liquids ([BMIM]PF6and [BMIM]BF4) are synthesized from N-methyl-midazolium, chlorobutane, KPF6and NaBF4under microwave irradiation and water bath heating respectively by two-step method and the structure characteristics, electrochemical performance are characterized by IR, TGA and XRD. Then, the two kinds of imidazole ionic liquids, as electrolyte, are applied to new chemical power source system with the potassium ferrate cathode.Hypochlorite is used as oxidant to synthesize potassium ferrate, the optimum preparation condition is fixed and the purity is97.5%. IR, XRD and SEM are used to demonstrate the sample.Open analogue battery composed with potassium ferrate as cathode, Zn as anode and10mol/L KOH aqueous solution or [BMIM]OH in ethanol solution as electrolyte is tested by CV, EIS and charge-discharge method to study the redox reversibility, interfacial properties specific energy, cycle life and the discharge performance at different rate. The results show that, it has large capacity and stable discharge curve, hopefully, it becomes alternative chemical power source of small-micro portable medical devices. Later, K2FeO4-Li button cells are composed in the glove box which is full of Ar gas and their performance at different discharge rate is tested, the results show that K2FeO4-Li button cells are only suitable for low discharge current condition; the specific capacity can reach350mAh/g, the EIS also indicates that the resistance of electric charge transmitting is large. Two kinds of ionic liquids are added into the electrolyte and the impact on the conductivity is studied, then the results show that, with the addition of [BMIMJPF6, the conductivity of the electrolyte decline linearly, but the conductivity of the electrolyte after adding [BMIM]BF4rises continuously. The initial voltage of K2FeO4-Li button cells with the electrolyte containing [BMIM]BF45%(volume fraction) change from1.7V to2.1V and the capacity is96%of original value.