Coulombic-hinderance regulation on pyrovanadates for practicable calcium-ion batteries: a solid-solution strategy

Area of Science:

• Materials Science
• Electrochemistry
• Solid-state Chemistry

Background:

• Pyrovanadates show promise for calcium-ion batteries (CIBs) due to their layered structure.
• Challenges in CIBs include slow Ca²⁺ diffusion and strong electrostatic interactions, hindering host material performance.

Purpose of the Study:

• To develop novel solid-solution pyrovanadate materials for enhanced CIB performance.
• To investigate the mechanism of improved Ca²⁺ ion diffusion and structural stability in these materials.

Main Methods:

• Synthesis of Zn₃₋ₓCuₓ(OH)₂V₂O₇·2H₂O solid solutions.
• Electrochemical testing of coin-cell CIB devices with an active carbon anode.
• Theoretical simulations and X-ray absorption spectroscopy for mechanistic studies.

Main Results:

• Solid-solution formation activated redox reactions at non-vanadium sites, creating a discharge/charge plateau.
• Enhanced interlayered confinement improved structural stability and facilitated Ca²⁺ ion diffusion.
• CIB devices demonstrated stable cycling over 1000 cycles at 100 mA g⁻¹.

Conclusions:

• Allelic reconfiguration strategy via solid-solution design is effective for creating Coulombic-force-resistant host materials.
• This approach addresses layer shrinkage issues in pyrovanadates for multivalent ion batteries.
• The developed materials show significant potential for advanced CIB technologies.