By copying the multilayer geometry of mammalian bones, the cathodes of sodium-ion batteries can be more structurally stable, while maintaining high capacities and fast charge rates.
Sodium-ion batteries are ready to replace lithium-ion batteries for large-scale electrical storage. They offer several advantages over lithium-ion batteries, mainly because they are high in sodium.
However, it is difficult to develop sodium cathodes, materials that can absorb electrons into the battery. Many of the candidate materials are unstable or unable to withstand high stresses.
To find the solution, researchers turned to nature at Sungkyunkwan University, the University of Texas at Austin and the Brookhaven National Laboratory. The journal describes a sodium cathode inspired by bone in mammals Applied Physics Reviews, By AIP Publishing.
“We believe that nature offers a very promising solution to technical problems,” said Ho Seok Park, one of the authors. “Therefore, we have tried to find the ideal architecture that can solve these kinetic and stable limitations.”
The bone structures of mammals are composed of a porous and spongy internal bone that allows the storage and transport of bone marrow, surrounded by a hard, dense bone that provides mechanical and structural integrity under severe stress.
Following this design architecture, the team created a porous system of Na3V2 (PO4) 3 structures, also known as NVP, surrounded by a compact compact shell. graphene oxide (rGO). NVP is a sodium cathode material that transports sodium ions rapidly but is structurally unstable.
The Bonelike configuration helps to improve the structural integrity of the system by reducing the permanent damage caused by electrochemical and mechanical stresses. Meanwhile, the combination of NVP and rGO creates a better environment for sodium ions, improving the stability of the system. The battery can be charged at very high speeds and retains more than 90% of its contents after 10,000 cycles have been discharged and recharged, depending on the charge rate.
Despite promising technical advances, the researchers noted that the work is currently only evidence of a concept that demonstrates the viability of a sodium cathode inspired by mammalian bones. Complementary work must be done to implement the technological uses of the system.
“High-quality bone-inspired NVP synthesis is expected to optimize bone-inspired NVP composition and structure, and the manufacture and testing of high-surface and high-charge electrodes is considered necessary for more practical applications,” Park said.
Reference: Kang Ho Shin, Sul Ki Park, Puritut Nakhanivej, Yixian Wang, Pengcheng Liu, Seong-Min Bak, Min Sung Choi, David Mitlin and Ho Seok Park, December 8, 2020, Applied Physics Reviews.
DOI: 10.1063 / 5.0020805