Alkaline hybrid redox flow battery with high energy density

Abstract

A novel high cycle life, low cost hybrid redox flow battery that has application in the storage of energy generated by solar cells, windmills and other means is described. By combining a solid battery positive electrode with a redox flow negative electrode, the volumetric energy density of the system is maximized and footprint minimized for medium scaled installations of multi kilowatt-hour size as may be envisioned in domestic distributed power systems. The positive electrode is a high cycle life rechargeable nickel hydroxide electrode in alkaline solution. The negative active material is a low cost organic chemical such as a substituted anthroquinone dissolved in an alkaline electrolyte and stored external to the negative plate of the electrochemical device. The material of the negative plate is high surface area and capable of facilitating the oxidation and reduction reactions of the negative active material. The negative and positive electrodes are separated by an electronically insulating but ionically conducting separator material that allows ionic mobility and the generation of electric current when charging or discharging of the battery takes place. Ideally, an ion exchange membrane would separate the positive and negative active material in order to maximize service life and reduce intermingling of active material.