New Strategy Proposed for High-Performance Cathodes in Aqueous Zinc Ion Batteries

A new strategy was proposed in the field of aqueous zinc ion battery to help increase the capacity of the cathodes, making them more efficient, according to a recent research published in ACS Nano.

"We transformed low-valence vanadium into high-valence vanadium in oxides using an electrochemical method," said Prof. HU Linhua, who led the team. He is from Hefei Institutes of Physical Science (HFIPS) of Chinese Academy of Sciences (CAS).

Aqueous Zinc-ion batteries (AZIBs) are a promising technology for large-scale stationary energy storage. To make this technology more viable for commercial use, researchers have developed innovative cathode materials to improve performance. Vanadium oxides (VO_x) have been widely considered as a favorable option for AZIBs. However, their low electronic conductivity and slow Zn²⁺ diffusion kinetics have posed challenges in showcasing the dominance of VO_x.

In this research, scientists constructed an in situ electrochemically induced phase transition to obtain high-performance aqueous zinc ion cathode materials.

They used a special process to change the structure of a material called V₆O₁₃ to V₅O₁₂·6H₂O when it is charged for the first time. This change made the material better at conducting electricity and allowed zinc ions to move more easily, which increased its ability to store energy. The modified material also had spaces that made it easier for particles to move around, and it remained stable over many charging cycles. As a result, the new material could be charged very quickly, had a high capacity for storing energy, performed well at high charging speeds, and lasted a long time without losing its ability to store energy.

This new method provides a new direction for resolving the challenges in developing high-performance cathodes for AZIBs, according to the team.

The electrochemically induced phase transformation behaviors of the V₆O₁₃ cathode. (Image by MO Li'e)

Comparison of band structure, energy gap, the density of states and diffusion energy barrier in V₆O₁₃ and V₅O₁₂·6H₂O. (Image by MO Li'e)