A new study published in journal Angewandte Chemie paves the way for using scrap metal in potassium-ion batteries thereby not only helping deal with the large amount of metal waste but also helping nature to a certain extent.
Researchers in China believe that while lithium-ion batteries are being extensively used now, there is a need to find much cheaper and greener solutions to tackle with the growing energy demands. Sodium ion batteries are being seen as an inexpensive alternative, but Chinese scientists believe potassium ion batteries as equally well suited for mass consumption.
However, there is one technical hurdle wherein the repeated storage and release of potassium ions destabilizes the materials currently used in electrodes. That’s where the latest study comes in as scientists have made good use of waste while finding an innovative solution to a technical problem by transforming rusty stainless steel mesh into electrodes with outstanding electrochemical properties that make them ideal for potassium-ion batteries.
Researchers from Chinese Academy of sciences and Jilin University (Changchun, China) have found an elegant solution in their use of a waste material to make novel electrodes: rejected stainless steel mesh from filters and sieves. Despite the excellent durability of these grids, harsh conditions do lead to some corrosion. The metal can be reclaimed in a furnace, but this process requires a great deal of money, time, and energy, as well as producing emissions.
The corroded mesh is dipped into a solution of potassium ferrocyanide (yellow prussiate of potash, known as a fining agent for wine). This dissolves iron, chromium, and nickel ions out of the rust layer. These combine with ferricyanide ions into the complex salt known as Prussian blue, a dark blue pigment that is deposited onto the surface of the mesh as scaffold-like nanocubes. Potassium ions can easily and rapidly be stored in and released from these structures.
The researchers then use a dip-coating process to deposit a layer of graphene oxide (oxidized graphite layers). This layer nestles tightly onto the nanocubes. Subsequent reduction converts the graphene oxide to reduced graphene oxide (RGO), which consists of layers of graphite with isolated oxygen atoms.
In tests, coin cells made with these new electrodes demonstrate excellent capacity, discharge voltages, rate capability, and outstanding cycle stability. Because the inexpensive, binder-free electrodes are very flexible, they are highly suitable for use in flexible electronic devices.