Open Source Electrical Energy Storage Device
In the realm of renewable energy storage, a fascinating idea has emerged – the Flow Battery, which combines electron current with fluid current. Recently, detailed open-source designs for a small, high energy density zinc-iodide flow battery have been made available by the Flow Battery Research Collective. Here's a step-by-step guide on how to build this battery, controlled by an open source potentiostat and Arduino.
**Cell Design**
The core of this battery is a central electrochemical cell, divided into two separated halves (anode and cathode compartments). Brass-backed grafoil, compressed graphite sheets, serve as current collectors. Graphite felt acts as porous electrodes to facilitate electrochemical reactions. A matte photo paper separator membrane is inserted between the two electrolyte chambers to prevent mixing yet allow ionic conduction. The cell frame and the electrolyte reservoirs are 3D printed from polypropylene for increased chemical resistance; supporting frame parts can be printed from any rigid filament.
**Electrolyte**
The main active materials in the electrolyte are aqueous solutions of zinc chloride and potassium iodide. During charge, zinc plates onto the cathode, while iodine and polyhalogen ions form in the anode compartment. Conversely, during discharge, plated zinc dissolves back, and iodine species are reduced back to iodides, completing the cycle.
**Fluid Handling**
Each half-cell has a reservoir and a peristaltic pump that circulates electrolyte through the cell compartments. The pumps are controlled by an Arduino microcontroller, enabling programmable control of flow rate synchronized with charge/discharge cycles.
**Electrochemical Control**
An open source potentiostat controls the battery’s charge and discharge by regulating current and voltage precisely. This setup enables measurement, cycling, and characterization without expensive commercial instruments.
**Additional Notes**
Before filling with active electrolyte, it is advisable to test the cell for leaks with distilled water because iodide ions can stain. The cell and system designs are documented openly by the Flow Battery Research Collective, accompanied by build instructions, parts lists, and community support forums.
High energy densities are achievable using this chemistry and configuration for scalable and low-cost flow battery projects. With this DIY guide, you can create a replicable, educational, and practical zinc-iodide flow battery with integrated control systems using Arduino and open source potentiostats.
[1] Flow Battery Research Collective. (n.d.). Small Zinc-Iodide Flow Battery. Retrieved from [Flow Battery Research Collective website](http://flowbatteryresearch.org/projects/small-zinc-iodide-flow-battery/)
[2] Flow Battery Research Collective. (n.d.). Open Source Potentiostat. Retrieved from [Flow Battery Research Collective website](http://flowbatteryresearch.org/projects/open-source-potentiostat/)
[4] Flow Battery Research Collective. (n.d.). Arduino-Controlled Peristaltic Pump. Retrieved from [Flow Battery Research Collective website](http://flowbatteryresearch.org/projects/arduino-controlled-peristaltic-pump/)
In this DIY guide, the zinc-iodide flow battery is controlled by an open source Arduino, a popular technology platform in the realm of science and technology. Moreover, this project is collaboratively developed under the open source philosophy, aligning with the science community's focus on sharing and advancing knowledge.
