Direct conversion of rusty stainless steel mesh into stable, low-cost electrodes for potassium-ion batteries

June 9, 2017

Chinese 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. As reported in the journal Angewandte Chemie, the rust is converted directly into a compact layer with a grid structure that can store potassium ions. A coating of reduced graphite oxide increases the conductivity and stability during charge/discharge cycles.

Increasing use of renewable energy requires effective energy storage within the grid. Lithium ion batteries, widely used in portable electronics, are promising candidates. Lithium ion batteries are based on the displacement of lithium ions. While charging, the ions move toward the graphite electrode, where they are stored between the layers of carbon. When discharging, they are released. However, lithium is expensive and reserves are limited. Sodium ion batteries have been explored as an alternative.

"Potassium ions are just as inexpensive and readily available as sodium, and potassium would be superior from the electric aspect," reports Xin-Bo Zhang. "However, the significantly larger radius of the has posed a problem. Repeated storage and release of these ions destabilizes the materials currently used in electrodes."

Zhang and a team from the Chinese Academy of sciences and Jilin University (Changchun, China) have now found an elegant solution in their use of a waste material to make novel electrodes: rejected 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. Says Zhang: "Conversion into electrodes could develop into a more ecologically and economically sensible form of recycling."

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 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 (RGO), which consists of layers of graphite with isolated oxygen atoms. Zhang explains, "the RGO coating inhibits clumping and detachment of the active material. At the same time, it significantly increases the conductivity and opens ultrafast electron-transport pathways."

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.

Explore further: Novel electrode materials have designed pathways for electrons and ions during the charge/discharge cycle

More information: Yun-hai Zhu et al. Transformation of Rusty Stainless-Steel Meshes into Stable, Low-Cost, and Binder-Free Cathodes for High-Performance Potassium-Ion Batteries, Angewandte Chemie International Edition (2017). DOI: 10.1002/anie.201702711

Related Stories

High storage batteries from sodium ion batteries

October 26, 2016

The mechanism of sodium ion storage in an important two-dimensional material could be a simpler and less toxic route to cheaper batteries, a team of KAUST researchers discovered.

Inexpensive material boosts battery capacity

October 23, 2013

Battery-powered cars offer many environmental benefits, but a car with a full tank of gasoline can travel further. By improving the energy capacity of lithium-ion batteries, a new electrode made from iron oxide nanoparticles ...

Recommended for you

Scientific advances can make it easier to recycle plastics

November 17, 2017

Most of the 150 million tons of plastics produced around the world every year end up in landfills, the oceans and elsewhere. Less than 9 percent of plastics are recycled in the United States, rising to about 30 percent in ...

The spliceosome—now available in high definition

November 17, 2017

UCLA researchers have solved the high-resolution structure of a massive cellular machine, the spliceosome, filling the last major gap in our understanding of the RNA splicing process that was previously unclear.

Ionic 'solar cell' could provide on-demand water desalination

November 15, 2017

Modern solar cells, which use energy from light to generate electrons and holes that are then transported out of semiconducting materials and into external circuits for human use, have existed in one form or another for over ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

rderkis
5 / 5 (1) Jun 09, 2017
[q[ rusty stainless steel mesh

I am not arguing with this study in the least! That would be very dumb on my part. I thought stainless steel does not rust.?
24volts
not rated yet Jun 11, 2017
By definition it doesn't but I wonder if these cells could be made at home. It doesn't sound all that complicated.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.