Improved low-cost, non-hazardous, all-iron cell for the developing world

A low-cost, non-hazardous personal-power system based on an aqueous all-iron electrochemical cell is demonstrated. The system is intended to be assembled and operated by developing-world households that lack sufficient access to electricity, thereby enabling LED lighting or mobile phone charging on demand. Lab-scale hardware is used to assess the performance of individual cell components. It is found that coffee filter paper is an effective low-cost separator. Carbon felt is a low-cost electrode material, and its performance and wetting by the electrolyte solution is greatly improved by pre-treatment with sulfuric acid. The carbon felt does not degrade after a week of daily use. By using these components, performance of the system is significantly improved over the previous baseline, with power density more than doubling to 40 mW cm−2, and iron utilization improving from 78% to 88%. The operating cost is estimated to be less than US$0.03 per mobile phone charge. Based on the lab-scale results, a stand-alone prototype consumer product is designed, fabricated, and tested. It successfully provides 2.5 h of LED illumination while consuming 200 mL of electrolyte solution via gravity feed. We anticipate these results will enable deployment of this innovative system to energy-impoverished individuals in the developing world.