Bifunctional perovskite electrocatalyst and PVDF/PET/PVDF separator integrated split test cell for high performance Li-O2 battery

Abstract

In this work, we have studied the electrochemical performance of split test cell based Li-O2 battery using PVDF/PET/PVDF nanofiber non-woven membrane and La0.5Ce0.5Fe0.5Mn0.5O3 perovskite (denoted as LCFMO) air cathode. The LCFMO air cathode is prepared by a simple wet chemical co-precipitation method and the PVDF/PET/PVDF nanofiber separator is synthesized by an electrospinning method. The as-prepared air cathode and PVDF/PET/PVDF separators are assembled in Li-O2 cell and their charge-discharge profile is evaluated at the potential window of 2–4.5 V at 100 mA g−1 with a limited capacity range of 300, 500 and 1000 mAh g−1. The result certified that the LCFMO-(Urea) catalyst based Li-O2 battery with PVDF/PET/PVDF separator showed an excellent cycling stability over 263, 147 and 120 cycles, respectively. This is due to the excellent bifunctional activity of LCFMO catalyst and high ionic transport properties of PVDF/PET/PVDF membrane. Also, the use of LiI redox mediator can effectively reduce the both charge and discharge overpotential of our Li-O2 battery system. The optimal pore size, higher porosity and good ionic conductivity of the PVDF/PET/PVDF membrane is also an essential factor for the enhanced performance of Li-O2 battery. In addition, AC impedance study evidenced that the Li-O2 battery shows much lower interfacial charge transfer resistance (i.e., lower Rct), which indicates the good electrochemical properties of our proposed materials.