Continuous Proton Channels in Vanadium Hexacyanoferrate Enable All-Round Improved Ultra-Low-Temperature Energy...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Proton-based batteries show potential for low-temperature applications but face cathode performance limitations.
• Developing efficient cathode materials is crucial for advancing ultra-low-temperature energy storage.

Purpose of the Study:

• To pioneer a novel proton cathode material, vanadium hexacyanoferrate with [Fe(CN)6] vacancies (VFeCN-VHCF), for improved ultra-low-temperature energy conversion.
• To investigate the mechanism of proton storage and conduction in the engineered cathode material.

Main Methods:

• Operando characterization techniques were employed to study the material's behavior.
• Density functional theory (DFT) calculations were used to understand the underlying mechanisms.
• Fabrication and testing of a full proton battery utilizing the novel cathode.

Main Results:

• The [Fe(CN)6] vacancies in VFeCN-VHCF induce V=O bonds, acting as active sites for proton storage and leading to high capacity.
• Continuous proton channels are formed via interactions between interstitial water and V=O-H groups, enabling rapid Grotthuss-type proton conduction.
• The fabricated VFeCN-VHCF||H2 proton full battery achieved a specific capacity of 165.16 mAh g-1 at 0.1 Ag-1.
• Remarkably, the battery maintained a high capacity of 86.63 mAh g-1 at -80 °C, outperforming existing low-temperature batteries.

Conclusions:

• The engineered VFeCN-VHCF material demonstrates excellent performance as a proton cathode for ultra-low-temperature energy storage.
• The developed proton channels and active sites are key to achieving high capacity and rapid proton conduction.
• This work presents a significant advancement for high-power energy storage systems operating in extreme environments.