A collection of researchers have invented a flexible, yarn-like battery prototype that uses the electrolytes in salty water to conduct electricity through ions.
The report was published in report in ACS Applied Materials and Interfaces by an international team consisting of Yihao Jian, Jun Ju, Lingwei Pei, Wenhu Gao, Duan Li, Wei Wang, Yan Qiao and Zhisong Lu.
Funding for the project came from the Chongqing Natural Science Foundation, the Sichuan Science and Technology Program, the Innovation Research 2035 Pilot Plan of Southwest University, and the Science and Technology Innovation Program of the General Administration of Sport of China.
Channeling ocean power
To create electrodes for the seawater batteries, the group treated carbon fiber bundles with electrically conductive coatings – nickel hexacyanoferrate for the positive electrode (cathode) and polyamide for the negative electrode (anode). Then researchers twisted two bundles together to form yarn-like cathode and anode strings.
To prepare a battery, the researchers wrapped the cathode string in a layer of fiberglass, laid it along the anode, and encased both strands in a nonwoven, permeable fabric. The fabric protects the electrodes while also letting in seawater to contact the electrodes.
In tests using salt water, the battery continued to store an electrical charge after being bent 4,000 times. Then, when evaluated in seawater, it retained most of the initial charging efficiency and storage capacity over 200 charge and discharge cycles.
Finally, as a proof-of-concept, the group knotted battery strands together into a fishing net and wove a rectangular piece of fabric. The net was then soaked in seawater to absorb the electrolyte and was charged. The net battery lit up a 10-LED panel. Similarly, the fabric submerged in a sodium sulfate solution powered a timer for more than an hour.
Research applications
These flexible, yarn-like batteries can be knit or woven into various shapes. The researchers highlight that their yarn-like battery has potential as an energy source in marine applications, such as powering lights on fishing nets, life jackets or mooring lines for buoys.
Yan Qiao, Zhisong Lu and colleagues previously developed a water-friendly battery made with carbon fiber and cotton yarn. This prior work used sweat from the body as the electrolyte for exercise monitors. Like sweat, seawater, which contains sodium, chloride and sulfate ions, can serve as an electrolyte.
In related news, a Research and Markets report predicts that the marine battery market will grow from US$882.3m to US$1.50bn from 2024 to 2030. Click here to read the full story.