KVOPO4 as Cathode for Sodium Ion Batteries

 Background: 

Sodium ion batteries have attracted much attention in recent years, due to the higher abundance and lower cost of sodium, as an alternative to lithium ion batteries. However, a major challenge is their lower energy density. In this work, we report a novel multi‐electron cathode material, KVOPO₄, for sodium ion batteries.

 Technology Overview: 

 we prepared a novel KVOPO₄ cathode that delivers a very promising multielectron charge storage in a sodium ion battery. The V³⁺ ↔ V⁵⁺ redox couple in the vanadyl phosphates was for the first time activated, intercalating 1.66 sodium ions per formula unit intercalation reaction. Structural characterization including X‐ray absorption spectroscopy, ex situ XRD revealed the highly reversible evolution of the polyhedron framework with a small volume change upon multiple sodium intercalation/extraction. The multielectron reaction and the small volume change enabled the discharge capacity of over 200 mAh g⁻¹ for this phosphate‐based compound with excellent capacity retention upon extended cycling. This capacity combined with an average voltage of 2.56 V delivers an energy density of over 600 Wh kg⁻¹, which exceeds that of the current sodium ion battery intercalation cathodes. Moreover, both rate capabilities and DFT calculations indicate that the sodium diffusion kinetics within the unique wide‐open vanadyl phosphate framework are quite facile, which could yield a high power cathode.

 Advantages: 

• Higher energy density (both gravimetric and volumetric)
• The phosphate group decreases the ease of oxygen release when fully charged, thus increasing the battery safety

 Intellectual Property Summary: 

US15/633,240