Open-Source Design for Energy Storage System: Flow Battery Edition
In a groundbreaking development for home energy storage, the Flow Battery Research Collective has recently released detailed instructions for building a small-scale zinc-iodide flow battery. This homemade battery design boasts energy densities similar to commercial models, making it an exciting option for DIY enthusiasts and renewable energy advocates alike.
The design features a central electrochemical cell divided into two compartments, separated by a membrane made from matte photo paper. The electrodes, serving as current collectors, are crafted from brass-backed grafoil (compressed graphite sheets), with graphite felt used as the porous electrodes. The cell frame and electrolyte reservoirs are 3D printed from chemically resistant polypropylene, with supporting structures printed from rigid filaments.
The electrolyte for this cell consists of zinc chloride and potassium iodide solutions. During charging, zinc deposits on one electrode (the cathode), while iodine and polyhalogen ions form in the opposite compartment (the anode). Conversely, during discharge, zinc redissolves in the anode compartment, and the iodine and polyhalogen ions are reduced back to iodides and chlorides.
An open-source potentiostat manages charge and discharge cycles, while peristaltic pumps, controlled by an Arduino, circulate electrolytes through the cell chambers. Researchers advise testing the cell for leaks with distilled water before filling it with electrolyte due to the stains that iodide ions can leave.
While other homemade flow cell designs exist, the zinc-iodide flow battery design from the Flow Battery Research Collective offers relatively high energy density (~25 Wh/L), making it one of the most promising options for DIY energy storage. Other homemade flow cell designs may lack detailed instructions or have lower performance.
Despite its promising potential, challenges such as long-term cycling issues with cell sealing and pump tubing degradation caused by iodide ions have been addressed in iterative cell designs.
Beyond zinc-iodide, other homemade flow battery research explores different chemistries such as manganese/iron systems. However, these currently tend to have lower energy densities or less straightforward construction than zinc-iodide systems.
For those interested in building this DIY flow cell, a forum is available to document progress or ask for advice on the specific project. The detailed instructions and open-source electronics make this an accessible and exciting project for DIY enthusiasts and renewable energy advocates.
- This zinc-iodide flow battery design, open to the public, is based on technology and uses data-and-cloud-computing through an Arduino to manage charge and discharge cycles.
- The design, originally from the Flow Battery Research Collective, is part of the open-source environmental-science community, providing the potential for further scientific advancements in the field of home energy storage.
- Aside from zinc-iodide, another focus in the world of DIY flow battery research is manganese/iron systems, although they tend to have lower energy densities or more complex constructions compared to the zinc-iodide design.
