Development of LiFePO4/FePO4 Electrode for Electro-Osmotic Pump using Li+ Migration

Abstract

Olivine structure of LiFePO4 (LFP) is one of the most commonly used materials in aqueous rechargeable lithium batteries (ARLBs), and can store and release charge through the insertion/de-insertion of Li+ between LFP and FP. We have fabricated LFP and LFP/FP electrodes on titanium paper and studied their electrochemical properties in 2 M Li2SO4. The LFP/FP electrode was determined to be a suitable electrode for electo-ostmotic pump (EOP) in terms of efficiency in water and 0.5 mM Li2SO4 solution. Experiments to determine the effect of cations and anions on the performance of EOP using LFP/FP electrode have shown that Li+ is the best cation and that the anion does not significantly affect the performance of the EOP. As the concentration of Li2SO4 solution was increased, the current increased. The flow rate peaked at 4.8 μL/30 s in 1.0 mM Li2SO4 solution and then decreased. When the EOP was tested continuously in 1.0 mM Li2SO4 solution, the EOP transported approximately 35 mL of fluid while maintaining a stable flow rate and current for 144 h. Keywords: Electro-osmotic pump (EOP), Aqueous rechargeable lithium-ion battery (ARLB), Lithium iron phosphate (LFP), Electrode, Lithium ion (Li+)