Sponge-Like Battery Structure Inspired by Mammalian Bones

Innovation: Academia

Sungkyunkwan University

2020

Image: DerWeg / Pixabay / CC BY SA - Creative Commons Attribution + ShareAlike

Prevent Fracture/Rupture

High force impact or stress can cause materials that comprise living systems to separate into two or more pieces (called fracturing) or to break or burst suddenly (called rupturing). For example, a scallop prevents structural failure from fracture because its shell is comprised of two materials of varying stiffness. When a crack moves from the scallop’s stiff material to the less stiff one, the latter reduces the force at the tip of the crack, thereby stopping it from spreading farther.

Search this Function

Transform Electrical Energy

Electric energy comes from electric potential energy, which is energy associated with a living system’s electric charge or its position relative to other electrically charged objects or living systems.

Search this Function

Prevent Deformation

When a living system undergoes compression, tension, shear, bending, or twisting, its internal inter-molecular forces can often resist these forces and even change shape temporarily, returning to the original shape when the forces stop. However, if the force is too strong or lasts too long, permanent deformation or structural failure can occur, resulting in death. Therefore, living systems have strategies to resist deformation or help ensure limited deformation. For example, bones have thin crystals and proteinaceous fibers that provide strength and flexibility, protecting them from forces that would otherwise cause deformation on a daily basis.

Search this Function

Battery from Sungkyunkwan University has a porous structure that remains stable at high voltages.

Benefits

Stable
Increased efficiency
Energy-saving

Applications

Energy supply & storage
Renewable energy

UN Sustainable Development Goals Addressed

Goal 9: Industry Innovation & Infrastructure
Goal 11: Sustainable Cities & Communities

The Challenge

Sodium-ion batteries have advantages over lithium-ion batteries because sodium is cheaper and much more available. However, they offer disadvantages as well. Sodium-ion batteries are heavier than lithium-ion batteries, making them less versatile and harder to work with. Additionally, sodium-ion batteries cannot handle the same voltage levels as lithium ones.

Innovation Details

The battery mimics the inner and outer structure of mammalian bones. Bones are porous on the inside to allow for the movement and transport of bone marrow. The outside is hard and compact, providing strength and support, especially in times of stress. Similarly, the battery has a sponge-like architecture made from a sodium cathode material called NVP (Na3V2(PO4)3), which is surrounded by a dense shell of reduced graphene oxide (rGO). NVP is excellent at transporting sodium and has a better cycling stability, a flatter voltage profile, and stronger thermal capabilities than common cathode materials. However, it is structurally unstable, so being encase in rGO provides support, while also facilitating charge transfer, which contributes to the high charging rate and long life cycle. Overall, the bonelike architecture makes the battery more structurally sound, reducing permanent damage from electrochemical and mechanical stress. The battery 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.

A schematic illustration of the design for a bone-inspired NVP cathode. Photo: Kang Ho Shin/Sungkyunkwan University.

Biological Model

Bones are made up of two types of tissue, a hard layer on the outside called compact tissue, and a spongey inner tissue called cancellous tissue. The compact tissue provides strength and support, especially in times of stress. The cancellous tissue is made of thin rods and plates arranged along lines of stress, creating a porous structure that protects against impact while also allowing for the movement and transport of bone marrow.

See Related Strategy

macro view of sponge like human bone structure

Biological Strategy

Fine Strands Stabilize Bones

Humans

The spongy bones of humans handle stress efficiently via the distribution of fine strands called trabeculae.

References

Journal article

Biomimetic composite architecture achieves ultrahigh rate capability and cycling life of sodium ion battery cathodes

Applied Physics Reviews

embedly preview

AskNature