Batteries mimic mammalian bones for added stability

Sodium-ion batteries are poised to replace lithium-ion batteries for large-scale electrical energy storage. They offer several advantages over lithium-ion batteries, particularly due to the widespread abundance of sodium.

However, it is difficult to develop sodium cathodes, materials through which electrons can enter a battery. Many candidate materials are unstable or cannot withstand high stresses.

To find a solution, researchers at Sungkyunkwan University, the University of Texas at Austin, and the Brookhaven National Laboratory turned to nature. They describe their sodium cathode inspired by mammalian bones in the journal Applied Physics Reviews.

“We believe that nature offers a very promising solution to solving technical problems,” said Ho Seok Park, one of the authors. “As a result, we tried to find the ideal architecture that could overcome these kinetic and stability limitations.”

Mammalian bone structures are made up of a porous and spongy internal bone which allows the storage and transport of the bone marrow, surrounded by a hard and compact bone, which provides mechanical and structural integrity under severe stress.

Following this design architecture, the group created a porous system of Na3V2 (PO4) 3 structures, also known as NVP, surrounded by a dense layer of reduced graphene oxide (rGO). NVP is a sodium cathode material that rapidly transports sodium ions but is structurally unstable.

The frame-like configuration helps improve the structural integrity of the system, reducing permanent damage from electrochemical and mechanical stress. Meanwhile, the combination of NVP and rGO creates a more favorable environment for sodium ions, improving the stability of the system. The battery can charge at ultra-high rates and maintain over 90% of its capacity after 10,000 discharge and recharge cycles, depending on the charge rate.

Despite these promising technical advances, the researchers note that the work is currently only a proof of concept demonstrating the feasibility of a sodium cathode inspired by mammalian bone. Additional work needs to be done to realize the technological uses of the system.

Large-scale synthesis of bone-inspired NVP with high quality, optimization of bone-inspired NVP composition and structure, as well as fabrication and testing of electrodes with large area and high load are considered necessary for more practical applications ”. Park said.