A schematic illustration demonstrating how the structure of a mammal bone is replicated in the design of the novel NVP cathode. Image: Kang Ho Shin, Sul Ki Park, Puritut Nakhanivej, Yixian Wang, Pengcheng Liu, Seong-Min Bak, Min Sung Choi, David Mitlin and Ho Seok Park.
A schematic illustration demonstrating how the structure of a mammal bone is replicated in the design of the novel NVP cathode. Image: Kang Ho Shin, Sul Ki Park, Puritut Nakhanivej, Yixian Wang, Pengcheng Liu, Seong-Min Bak, Min Sung Choi, David Mitlin and Ho Seok Park.

Sodium-ion batteries are poised to replace lithium-ion batteries for large-scale electrical energy storage. This is because they offer several advantages over lithium-ion batteries, particularly due to the widespread abundance of sodium. But developing cathodes for sodium-ion batteries has proved difficult, as many candidate materials are unstable or cannot withstand high voltages.

To find a solution, researchers from the University of Texas at Austin, Brookhaven National Laboratory and Sungkyunkwan University in Korea turned to nature. They describe the resulting mammal bone-inspired sodium cathode in a paper in Applied Physics Reviews.

"We believe that nature provides a very promising solution to resolve technical problems," said Ho Seok Park from Sungkyunkwan University, who is one of the authors of the paper. "Accordingly, we tried to find the ideal architecture that can resolve these kinetic and stability limitations."

Mammal bones comprise a porous, spongy bone material, which allows the storage and transport of bone marrow, surrounded by a hard, compact bone material, which offers mechanical and structural integrity under severe stress. Replicating this design architecture, the researchers created a porous system comprising a sodium-based conductor (Na3V2(PO4)3, also known as NVP), surrounded by a dense shell of reduced graphene oxide (rGO). NVP can transport sodium ions rapidly but is structurally unstable.

This bone-like design helps to improve the structural integrity of the system, reducing permanent damage caused by electrochemical and mechanical stress. Furthermore, the combination of NVP and rGO creates a more favorable environment for sodium ions, enhancing the stability of the system. A sodium battery with this cathode can charge at ultrahigh rates and maintain over 90% of its capacity after 10,000 cycles of discharging and recharging, depending on the charge rate.

Despite these promising technical advances, the researchers note this work is currently just a proof of concept to demonstrate the feasibility of a sodium cathode inspired by mammal bone. Additional work needs to be done to develop the system into a practical battery technology.

"A large-scale synthesis of bone-inspired NVP with high quality, the optimization of bone-inspired NVP composition and structure, and the fabrication and test of electrodes with large area and high loading are thought to be required for more practical applications," Park said.

This story is adapted from material from the American Institute of Physics, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.