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.

Image: Kang Ho Shin / Sungkyunkwan University / Copyright © ‑ All rights reserved

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

Biomimicry Story

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.