Investigation Of Composite Electrolyte Material And Its Electrochemical Performance For Lithium Air Battery

At present, environmental pollution and energy shortages are worsening. Lithium air battery have received attention of scholars and researchers all over the world because of its high energy density, especially organic system. The development of lithium air battery has been restricted by the problems of solvent evaporation, electrolyte decomposition, lithium anode corrosion and cathode space jam. The electrolyte, the anode material and cathode protection are hotspots of research. One of the problems of the present study is how to improve the battery performance on the basis of improving the stability of the electrolyte.This paper mainly studies the composite electrolyte materials and its application in lithium air battery, hoping to find an organic composite electrolyte material with efficient electrochemical properties. We systematically investigate the impacts of solute and solvent on lithium air battery by analyzing conductivity, viscosity, impedance, cyclic voltammetry, constant current charge and discharge, power characteristics and energy characteristics. At last, conclusions as follows:(1) While using EC/EMC/DMC as organic solvents with Li PF6, Li PF6-Li TFSI, Li PF6-Li BF4 as solute, the lithium air battery with Li PF6-Li BF4- EC/EMC/DMC composite electrolyte shows the best performance which can get the first discharge specific capacity 3163 m Ah g-1at the current density of 0.1 m A cm-2 and stable out voltage at current density of 0.01—0.25 m A cm-2. This makes the system has high research value. However, the cycle performance of the composite electrolyte is poorer, so it is necessary to optimize Li PF6-Li BF4- EC/EMC/DMC composite electrolyte to obtain highly cycle performance.(2)While using Li PF6 as solute with EC/EMC/DMC, EC/EMC/DMC-[Emim]BF4 and EC/EMC/DMC-[DEME]TFSI as organic, the lithium air battery with Li PF6- EC/EMC/DMC-[Emim]BF4 composite electrolyte shows the best performance which can get the first discharge specific capacity 2672 m Ah g-1at the current density of 0.025 m A cm-2 and stably cycle 15 circles.(3) While using Li PF6-Li BF4 as solute with EC/EMC/DMC-[Emim]BF4 as organic, the lithium air battery with Li PF6- EC/EMC/DMC-[Emim]BF4 composite electrolyte can get the first discharge specific capacity 2959 m Ah g-1at the current density of 0.1 m A cm-2 and stably cycle more than 30 circles. However, due to the introduction of ionic liquid, the lithium air battery only suitable work when the current density is not greater than 0.1 m A cm-2.