Description:
This invention introduces potassium vanadium phosphate (KVOPO₄) as a novel sodium-ion battery cathode. Its tunnel structure enables multi-electron redox reactions, achieving a practical capacity of 181 mAh/g with stable cycling and distinct voltage plateaus. By using abundant sodium instead of lithium, it provides a safer, scalable, and cost-effective pathway to high-performance energy storage.
Background:
Sodium-ion batteries are gaining interest as a low-cost, safer alternative to lithium-ion technology. However, their development has been constrained by limited energy density, as most cathode materials can only host a single sodium ion per formula unit. The larger size of sodium ions further hinders diffusion and cycling stability, preventing sodium-ion batteries from matching the performance of lithium-ion systems. A new cathode material that supports multi-electron reactions is needed to unlock higher capacity and enable broader commercial adoption.
Technology Overview:
This invention leverages potassium vanadium phosphate (KVOPO₄) synthesized through a solid-state reaction followed by ball-milling with carbon to enhance conductivity. Its orthorhombic tunnel structure supports insertion and extraction of more than one sodium ion per formula unit, engaging both V⁵⁺/V⁴⁺ and V⁴⁺/V³⁺ redox couples. This mechanism delivers a practical discharge capacity of 181 mAh/g and two voltage plateaus (~3.8 V and ~2.0 V vs. Na/Na⁺). Unlike typical sodium cathodes that undergo two-phase reactions, KVOPO₄ exhibits a solid-solution mechanism, improving structural stability and long-term cycling performance.
Advantages:
• Multi-electron redox storage, enabling higher capacity than conventional sodium cathodes
• Practical discharge capacity of 181 mAh/g with distinct 3.8 V and 2.0 V plateaus
• Solid-solution mechanism improves stability and cycle life
• Higher volumetric and gravimetric energy density compared to other sodium cathodes
• Uses earth-abundant, low-cost sodium instead of lithium
• Safer operation compared to conventional lithium-ion chemistries
Applications:
• Residential and off-grid solar storage for cost-effective energy independence
• Grid-scale renewable energy storage at reduced cost per kWh
• Affordable light electric vehicles (e-scooters, compact EVs)
• Marine electrification and stationary storage for ports and vessels
• Portable electronics needing safe, lower-cost alternatives to lithium-ion
Intellectual Property Summary:
• US Provisional Application 62/355,639 – Filed June 28, 2016 (Converted)
• US Patent 11,289,700 – Application 15/633,240, Filed June 26, 2017, Issued March 29, 2022, Published US 2017-0373310 A1
• US Patent 11,894,550 – Application 17/705,780, Filed March 28, 2022, Issued February 6, 2024, Published US 2022-0223846 A1
• US Application 18/432,831 – Filed February 5, 2024, Published US 2024-0222609 (Pending)
Stage of Development:
Lab validation – Coin cells demonstrated practical capacity of 181 mAh/g with multi-electron operation and improved stability compared to conventional sodium-ion cathodes. TRL ~4.
Licensing Status:
This technology is available for licensing.
Licensing Potential:
Attractive to energy storage manufacturers and EV developers seeking cost-effective, cobalt-free, high-capacity cathode solutions for sodium-ion platforms.
Additional Information:
Electrochemical cycling data, structural characterization, and synthesis methods are available upon request.
Inventors:
Jia Ding, M. Stanley Whittingham