A new flow-type cell by the application of magnetic microfluidic chip

Abstract

Using a magnetically formed channel called a magnetic channel, a new flow-type cell is proposed. The magnetic channel consists of magnetic walls that are formed by heterogeneous distributions of magnetic flux density around a ferromagnetic track under a magnetic field. The magnetic wall separates the paramagnetic oxidant solution from the diamagnetic reductant solution at a liquid–liquid interface without any solid membranes. In the magnetic channel formed on the cathode, the oxidant solution flows in a quasi-frictionless mode. The anode is placed in the reductant solution surrounding the magnetic channel. Such a geometrical configuration between the oxidant and reductant solutions is interchangeable depending on the magnetism of the solutions. To examine this concept, a Daniel cell system was adopted, where the copper ion in copper sulfate solution is employed as the oxidant and the zinc atom of zinc electrode as the reductant. The copper ion is paramagnetic, so that 1 mol dm−3 copper sulfate solution is injected into the magnetic channel formed on the copper cathode. Zinc sulfate solution (1 mol dm−3; diamagnetic) together with the zinc anode are placed surrounding the magnetic channel. The performance of this flow-type battery was examined up to a current density of 22 mA cm−2.